Category: Entrance Exam

JEE Main Previous Year Papers Questions With Solutions Chemistry Solutions and Colligative Properties

1.Freezing point of an aqueous solution is (- 0.186)°C Elevation of boiling point of the same solution is K_b = 0.512°C, Kr = 1.86°C, And the increase in boiling point. (2002)
1)186°C               2)    0.0512°C
3) 0.092°C          4)     0.2372°C
Ans.

2.With increase of temperature, which of these changes ?  (2002)
1) molality
2) weight fraction of solution
3) fraction of solute present in water
4) mole fraction
Ans.(3)Volume increases with rise in temperature

Ans.

4.If liquids A and B form an ideal solution
1)the enthalpy of mixing is zero (2003)
2)the free energy of mixing is zero
3)the free energy as well as the entropy of mixing are each zero
4)the enthalpy of mixing is zero
Ans.

5.25ml of a solution of barium hydroxide on titration with a 0.1 molar solution of hydrochloric acid gave a litre value of 35 ml. The molarity of barium hydroxide solution was        (2003)
1)14 2) 0.28             3) 0.35              4) 0.07
Ans.

6.A pressure cooker reduces cooking time for food because  (2003)
1)boiling point of water involved in cooking is increased
2)the higher pressure inside the cooker crushes the food material
3)cooking involves chemical changes helped by a rise in temperature
4)heat is more evently distributed in the cooking space
Ans.(1) On increasing pressure, the temperature is also increased. Thus in pressure cooker due to increase in pressure the b.p. of water increases.

7.Which one of the following aqueous solutions will exhibit highest boiling point ?         (2004)
1)01 M Na₂S0₄                    2) 0.015 M glucose
3) 0.015 M urea                    4) 0.01 M KN0₃
Ans.

8.To neutralize completely 20 mL of 0.1 M aqueous solution of phosphorous acid (H₃P0₃), the volume of 0.1 M aqueous KOH solution required is      (2004)
1)10 mL                      2) 60 mL
3) 40 mL                    4) 20 mL
Ans.

9.For which of the following parameters the structural isomers C₂II₅OH and CH₃OCH₃ would be expected to have the same values? (assume ideal behaviour)      (2004)
1)Heat of vaporization
2)Gaseous densities at the same temperature and pressure
3)Boiling points
4)Vapour pressure at the same temperature
Ans.(2) The molecular weight of C₂H₅OH and CH₃OCH₃ are same. So in its vapour phase at same temperature and pressure, the densities of both the substances will be same.

10.Which of the following liquid pairs shows a positive deviation from Raoult’s law? (2004)
1)Water – hydrochloric acid
2)Acetone – chloroform
3)Water – nitric acid
4) Benzene-methanol
Ans.(4) Benzene in methanol breaks the hydrogen bonding of the alcohol making its boiling point decrease and there by its vapour pressure increases leading two +ve deviation.

Ans.(2) Dependency on concentration as well as nature of solute.

Ans.

13.Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20°C for a solution containing 78 g of benzene and 46 g of toluene in torr is (2005)
1)50   2)25        3)37.5    4)53.5
Ans.

14.Two solutions of a substance (non-electrolyte) are mixed in the following manner. 480 ml of 1.5 M first solution + 520 mL of 1.2 M second solution. What is the molarity of the final mixture ?     (2005)
1) 1.20 M                       2) 1.50 M
3) 1.344 M                      4) 2.70 M
Ans.(3) The molarity of the mixture is in between those of the solutions mixed.

15. Equimolar solutions in the same solvent have (2005)
1)Same boiling point but different freezing point
2)Same freezing point but different boiling point
3)Same boiling and same freezing points
4)Different boiling and different freezing points
Ans.(3) Same properties of boiling and freezing

16.18 g of glucose (C₆H₁₂0₆) is added to 178.2 g of water. The vapour pressure of water for this aqueous solution at 100°C is (2006)
1) 759.00 Torr   2) 7.60 Torr
3) 76.00 Torr      4) 752.40 Torr
Ans.

17.Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is (2006)
1) 1.14     mol kg^-1                2)     3.28 mol kg^-1
3) 2.28      mol kg^-1                4)      0.44 mol kg^-1
Ans.(3) One litre solution has 2.05 mol of solute and 960g of solvent.

18.A 5.25% solution of a substance is isotonic with a 1.5% solution of urea (molar mass = 60g mol^-1) in the same solvent. If the densities of both the solutions are assumed to be equal to l.Og cm^-3, molar mass of the substance will be        (2007)
1) 90.0     g mol^-1                   2)     115.0 g mol^-1
3) 105.0 g mol^-1                     4)     210.0 g mol^-1
Ans.

19.The density (in g mL^-1) of a 3.60 M sulphuric acid solution that is 29% H₂SQ₄ (Molar mass = 98 g mol^-1) by mass will be            (2007)
1) 1.64           2) 1.88             3) 1.22            4) 1.45
Ans.

20.A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of 290 mm at 300 K. The vapour pressure of propyl alcohol is 200 mm. If the mole fraction of ethyl alcohol is 0.6, its vapour pressure (in mm) at the same temperature will be    (2007)
1)350             2)300               3)700              4)360
Ans.

21.At 80°C, the vapour pressure of pure liquid ‘A’ is 520 mm Hg and that of pure liquid ‘B’ is 1000 mm Hg. If a mixture solution of ‘A’ and ‘B’ boils at 80°C‘and 1 atm pressure, the amount of ‘A’ in the mixture is (1 atm = 760 mm Hg)      (2008)
1) 52 mol percent           2) 34 mol percent
3) 48 mol percent           4) 50 mol percent
Ans.

22.The vapour pressure of water at 20°C is 17.5 mm Hg. If 18 g of glucose (C₆H₁₂O_s) is added to 178.2g of water at 20°C, the vapour pressure of the resulting solution will be (2008)
1) 17.675 mm Hg    2)         15.750 mm Hg
3) 16.500 mm Hg             4)  17.325 mm Hg
Ans.

23.Two liquids X and Y form an ideal solution. At 300 K, vapour pressure of the solution containing 1 mol of X and 3 mol of Y is 550 mm Hg. At the same temperature, if 1 mol of Y is further added to this solution, vapour pressure of the solution increases by 10 mm Hg. Vapour pressure (in mm Hg) of X and Y in their pure states will be, respectively(2009)
1) 200 and 300                2)  300 and 400
3) 400 and 600                4)  500 and 600
Ans.

24.A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution ?    (2009)
1)The solution formed is an ideal solution
2)The solution is non-ideal, showing +ve deviation from Raoult’s law.
3)The solution is non-ideal, showing -ve deviation from R aoult’s law.
4)n-Heptane shows +ve deviation while ethanol show -ve deviation from Raoult’s law
Ans.(2) The interactions between n-heptane and  ethanol are weaker than that in pure components.

Ans.

26.On mixing, heptane and octane form an ideal solution. At 373 K, the vaopur pressure of the two liquid components (heptane and octane) are 105 kPa and 45 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0g of heptane and 35g of octane will be (molar mass of heptane = lOOg mol^-1 and of octane = 114 g mol^-1).   (2010)
1) 72.0 kPa          2)   36.1  kPa
3) 96.2 kPa        4) 144.5    kPa
Ans.

27.A 5.2 molal aqueous solution of methyl alcohol, m CH₃OH, is supplied. What is the mole fraction !; of methyl alcohol in the solution ?    (2011)
1) 0.086                         2)   0.050
3) 0.100                         4)   0.190
Ans.

28.Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to 4 kg of water to prevent it from freezing at – 6°C will be : (K_f for water = 1.86 K kg mol^-1, and molar mass of ethylene glycol = 62 g mol^-1)     (2011)
1) 400.0 g                      2) 304.60 g
3) 804.32 g                     4) 204.30 g
Ans.

Ans.

30.The density of a solution prepared by „ dissolving 120g of urea (mol. mass = 60u) in j; 1000 g water is 1.15 g/mL. The molarity of this solution is     (2012)
1) 0.50 M                                2) 1.78 M
3)1.02 M                                4) 2.05 M
Ans.

31.K_f for water is 1.86 K kg mol^-1. If your automobile radiator holds 1.0 kg of water, how many grams fo ethylene glycol (C₂H₆0₂) must you add to get the freezing point of the solution lowered to -2.8°C ?       (2012)
1) 72 g 2) 93 g 3) 39 g 4) 27 g
Ans.

32.The molarity of a solution obtained by mixing 750mL of 0.5(M) HC/ with 250 mL of 2(M) HO will be   (2013)
1) 0.875 M                     2) 1.00 M
3) 1.75M                        4) 0.975 M
Ans.

33.Consider separate solutions of 0.500 M C₂H₅OH(aq), 0.100M Mg₃(P0₄)₂(aq), 0.250M KBr(aq) and 0.125M Na₃P0₄(aq) at 25°C. Which statement is true about these solutions, assuming all salts to be strong electrolytes ?(2014)
1)500M C₂H₅OH(aq) has the highest osmotic pressure
2)They all have the same osmotic pressure
3)100 M M₃(P0₄)₂(aq) has the highest osmotic pressure
4) 0.125M Na₃P0₄(aq) has the highest osmotic pressure
Ans.

34.The vapour pressure of acetone at 20° is 185 torn When 1.2 g of a non-volatile substance was dissolved in 100 g of acetone at 20°C, its vapour pressure was 183 torn The molar mass (g mo/^-1) of the substance is       (2015)
1) 32           2) 64           3) 128         4) 488
Ans.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry  General Organic Chemistry

1.Arrangement of (CH₃)₃– C-, (CH₃)-CH-, CH₃– CH₂-, when attached to benzyl or an unsaturated group, in increasing order of inductive effect is (2002)
1)(CH₃)₃-C – < (CH₃)₂ – CH – < CH₃ – CH₂
2)CH₃-CH₂ – < (CH₃)₂ – < CH – < (CH₃)₃-C –
3)(CH₃)₂ – CH < (CH₃)₃ – C -< CH₃ – CH₂
4)(CH₃)₃ – C -< CH₃ – CH2 < (CH₃)₂ – < CH
Ans.(2) -CH₃ group has + I effect, as number of -CH₃ group increases, the inductive effect increases.

2.Which of the following does not show geometrical isomerism ? (2002)
1)1, 2 – dichloro – 1 – pentane
2)1,3- dichloro – 2 – pentane
3)1,2- dichloro – 1 – pentane
4)1, 4 – dichloro – 2 – pentane
Ans.

3.A similarity between optical and geometrical isomerism is that           (2002)
1)each forms equal number of isomers for a given compound
2)If in a compound one is present then so is the other
3)both are included in stereoisomerism
4)they have no similarity
Ans.(3) Optical and geometrical isomers are stereoisomers.

4.Which of the following compounds has wrong IUPAC name ?           (2002)

Ans.(3) Correct name is 3-methyl – 2-butanol.

5. Racemic mixture is formed by mixing two
1)isomeric compounds (2002)
2)chiral compounds
3)meso compounds
4)optical isomers
Ans.(4) Racemic mixture is formed when enantiomers are mixed in equimolar proportion.

6.The IUPAC name of CH₃COCH(CH₃)₂ is
1)2-methyl-3-butanone (2003)
2)4-methylisopropyl ketone
3)3-methyl-2-butanone
4)Isopropylmethyl ketone
Ans.

7.3The general formula C_nH_2n0₂ could be for open chain (2003)
1) carboxylic acids       2) diols
3) dialdehydes              4) diketones
Ans.(1) Carboxylic acid or ester.

8.Among the following four structures I to IV.it is true that  (2003)

1)only I and II are chiral compounds
2)only III is a chiral compound
3)only II and IV are chiral compounds
4)all four are chiral compounds
Ans.(1) A chiral object or structure has four different groups attached to the carbocation.

9.The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is  (2004)
1) Fe₄[Fe(CN)₆]₃           2) Na₄[Fe(CN)₅NOS]
3) Fe(CN)₃                    4) Na₃[Fe(CN)₆]
Ans.(1) Prussian blue coloured complex compound is ferric ferrocyanide.

10.The IUPAC name of the compound (2004)

1)3,3- dimethyl -1- hydroxycyclohexane
2)1,1 – dimethyl -3- cyclohexanol
3)3,3- dimethyl -1- cyclohexanol
4)1,1 – dimethyl -3- hydroxycyclohexane
Ans. (2)Methyl groups are at position 3.

11.Which one the following does not have sp² hybridized carbon ?  (2004)
1)Acetone                                2) Acetamide
3) Acetonitrile                       4) Acetic acid
Ans.(3) It is having only sp³ and sp hybridized carbon atom.

12.Which of the following will have meso-isomer also ? (2004)\
1)2- chlorobutane
2)2- hydroxyopanoic acid
3)2,3- dichloropentane
4)2-3- dichlorobutane
Ans.

13. Amongst the following compound, the optically active alkane having lowest [ molecular mass is       (2004)

Ans.

14.Which of the following compound is not chiral?  (2004)
1)1-chloropentane’
2)3-chloro-2-methyl pentane
3)1-chloro -2-methyl pentane
4)2-chloropentane
Ans.

15.Due to the presence of an unpaired electron, free radicals are (2005)
1)Chemically reactive   2) Chemically inactive   3) Anions 4) Cations
Ans.(1) Free redicals are chemically active.

16.The decreasing order of nucleophilicity among the nucleophiles         (2005)

Ans.(4) Highest n cloud is present in CN-

17.Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is (2005)
1)n-hexane     2)    2, 3-dimethylbutane
3) 2,2-dimethylbutane    4)   2-methylpentane
Ans.

18.Which types of isomerism is shown by 2,3-dichlorobutane ?   (2005)
1)Diastereo         2)    Optical
3) Geometric     4)    Structural
Ans.

Ans.(3) Double bond is given higher preference

20.The increasing order of stability of the following free radicals is   (2006)

Ans.(1) Triphenyl free radical is most stable.

21.Increasing order of stability among the three main conformations (i.e. Eclipse, Anti, Gauche) of 2-fluoroethanol is    (2006)
1)Eclipse, Gauche, Anti
2)Gauche, Eclipse, Anti
3)Eclipse, Anti, Gauche
4)Anti, Gauche, Eclipse
Ans.(3) Eclipse is least stable and gauche is most stable.

22.Which of the following molecules is expected to rotate the plane of plane polarized light? (2007)

Ans.(1) The plane of polarized light is rotated by optically active compound. Compound should be chiral.So, option (1) has, chiral C-atom. So, it is optically active.In (2), (3) and (4) plane of symmetry is present.

23.Which one of the following conformation of cyclohexane is chiral ? (2007)
1) Twist boat               2) Rigid
3) Chair                        4) Boat
Ans.(1) Twisted boat is chiral as it does not have plane of symmetry.

Ans.

Ans.

26.The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is(2008)
1)- COOH, – S0₃H, – CONH₂, – CHO
2)- SO3H, – COOH, – CONH2, – CHO
3)- CHO, – COOH, – S0₃H, – CONH,
4)- CONH₂, – CHO, – S0₃H, – COOH
Ans. (2) – S0₃H, – COOH, – CONH₂, – CHO

Ans.(3) 2° carbanion js more stable than 3°. Chlorine causes-I effect

28.The alkene that exhibits geometrical isomerism is      (2009)
1) propene                             2) 2-methyl propene
3) 2-butene                            4) 2-methyl -2-butene
Ans.

29.The number of stereoisomers possible for a compound of the molecular formula CH₃ – CH = CH – CH(OH) – Me is (2009)
1) 3                   2) 2             3) 4           4) 6
Ans.(3) About the double bond, two geometrical v isomers are possible and the compound is m having one chiral carbon.

30.The IUPAC name of  neopentane is (2009)
1) 2-methylbutane  2) 2, 2-dimethylpropane  3) 2-methylpropane  4) 2, 2-dimethylbutane
Ans.

31.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl’s method and the evolved ammonia was absorbed in 20 mL of 0.1 M HC1 solution. The excess of the acid required 15mL of 0.1 M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is (2010)
1) 59.0       2) 47.4        3) 23.7        4) 29.5
Ans.

32.Out of the following, the alkene that exhibits optical isomerism is (2010)
1)3 – methyl- 2 – pentane
2)4 – methyl – 1- pentane
3)3 – methyl – 1 – pentane
4)2 – methyl – 2 – pentane
Ans.

33.Identify the compound that exhibits tautomerism (2011)
1) 2 – Pentanone  2) Phenol  3) 2 – Butene            4) Lactic acid
Ans.

34.How many chiral compounds are possible on monocblorination of 2-methylbutane ? (2012)
1) 8      2) 2      3) 4      4) 6
Ans.

35.A solution of (-1) – 1 – 1 – chloro-1- phenylethane in toluene racemises slowly in the presence of a small amount of SbCl₅, due to the formation of    (2013)
1) carbanion                  2) carbene
3) carbocation               4) free radical
Ans.

Ans.(4) Primary carbocation is less stable.

37.For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia was M /10 absorbed in 60mL of M/10 sulphuric acid. The unreacted acid required 20 mL of — sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is(2014)
1) 5 %        2) 6%         3) 10%        4) 3%
Ans.

Ans.

Ans.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry  Alcohols,Ethers,Carobonyls and Carboxylic Acids

Ans.

Ans.(2) Aldehydic group gets oxidised to carboxylic group. Doyble bond breaks and carbon gets oxidised to carboxylic group.

3.An ether is more volatile than an alcohol having the same molecular formula. This is due to        (2003)
1)alcohols having resonance structures
2)inter-molecular hydrogen bonding in ethers
3)inter-molecular hydrogen bonding in alcohols
4) dipolar character of ethers
Ans.(3) Alcohols are associate liquids.

4.When CH₂ = CH – COOH is reduced with  LiAlH₄, the compound obtained will be (2003)
1)CH₂ = CH-CH₂OH ‘
2)CH₃ – CH₂ – CHjOH
3)CH₃ – CHj – CHO
4)CH₃ – CH₂ – COOH
Ans.(1) LiA/H₄ can reduce COOH group and not the double bond.
CH₂ = CH – COOH is reduced to give CH₂ = CH – CH2OH

5.During dehydration of alcohols to alkenes by heating with cone. H₂S0₄ the initiation step is (2003)
1)formation of carbocation
2)elimination of water
3)formation of an ester
4)protonation of alcohol molecule
Ans.

6.Consider the apidity of the carboxylic acids: Most acidic is    (2004)
1)PhCOOH
2)o – N0₂C₆H₄C00H
3)p – N0₂C₆H₄C00H
4)m – N0₂C₆H₄C00H
Ans.(2) Orthonitrobenzoic acid.

7.On mixing ethyl acetate with aqueous sodium chloride, the composition of the resultant solution is   (2004)
1)CH₃COOC₂H₅ + NaCl
2)CH₃C1 + C₂H₅COONa
3)CH3COCl + C₂H₅OH + NaOH
4)CH₃COONa + C₂H₅OH
Ans.(1) No chemical reaction occurs.

8.Acetyl bromide reacts with excess of CH₃MgI followed by treatment with a saturated solution of NH₄C1 given            (2004)
1)acetone                 2)   acetyl iodide
3)2-methyl-2-propanol      4)acetamide
Ans.(3) Gives tertiary alcohol.

9.Which of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid ? (2004)
1)Phenol                              2)   Benzoic acid
3) Butanal                          4) Benzaldehyde
Ans.(4)Benzaldehyde does not contain a-hydrogen. Hence goes for cannizarro’s reaction forming alcohol and acid.

10.Among the following compound which can be dehydrated very easily is         (2004)

Ans.(3) Tertiory alcohols will undergo more easily dehydration than secondary and primary.

11.The best reagent to convert pent-3- en-2-ol into pent-3-en-2-one is    (2005)
1) Acidic permanganate
2)Acidic dichromate
3)Chromic anhydride in glacial acetic acid
4)Pyridinium chloro – chromate
Ans.(3) Conversion of 2° alcohol to ketone with mild oxidant.

12.Among the following acids which has the lowest pK_a value?
1)CH₃COOH                     2) HCOOH
3) (CH₃)₂COOH              4) CH₃CH₂COOH
Ans.(2) Most acidic is formic acid.

13.Reaction of cyclohexanone with dimethyl- amine in the presence of catalytic amount of
an acid forms a compound if water during the reaction is continuously removed. The compound formed is generally known as (2005)
1) a Schiff’s base         2) an enamine
3) an imine                    4) an amine
Ans.

14.p-cresol reacts with chloroform in alkalin medium to give the compound A which adds
hydrogen cyanide to form, the compound B. The latter on acidic hydrolysis gives chiral carboxylic acid. The structure of the carboxylic acid is   (2005)

Ans.

15.The increasing order of the rate of HCN addition to compounds A – D is           (2006)
(A) HCHO                    (B) CH3COCH3
(C) PhCOCHj               (D) PhCOPh
1)A<B<C<D      2)D<B<C<A
3)D<C<B<A       4)C<D<B<A
Ans.(3) Least  reactive is PH-CO-PH.

16. Phenyl magnesium bromide reacts with methanol to give(2006)
1)a mixture of anisole and Mg(OH)Br
2)a mixture of benzene and Mg(OMe)Br
3)a mixture of toluene and Mg(OH)Br
4)a mixture of phenol and Mg(Me)Br
Ans.(2) Benzene is formed.

Ans.(4) Iodoform is given by methyl ketone.

18.The correct order of increasing acid strength of the compounds is
a)CH₃C0₂H    b) Me0CH₂C0₂H
c) CF₃Co₂H       d) (Me)₂ C0₂H
Ans.(3) CFjCOOH is most acidic.

19.The structure of the compound that gives a tribromo derivative on treatment with  bromine water is (2006)

Ans.(1) ortho and para positions of bromiantion, to -OH group.

Ans.(2) Dichlorocarbene is electrophile in Reimer- Tiemann reaction.

Ans.

Ans.(3) Any aliphatic carbon with hydrogen attached to it, in combination with benzene ring, will be oxidized to benzoic acid by KMn0₄ / H⁺.

Ans.

24.A liquid was mixed with ethanol and a drop of concentrated H.SO. was added. A compound with a fruity smell was formed. The liquid was        (2009)
1) CH₃OH                     2) HCHO
3) CH₃COCH₃                4) CH₃COOH
Ans.

25.The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is    (2009)
1) benzoic acid                   2) salicylaldehyde
3) salicylic acid                  4)phthalic acid
Ans.

26.Which of the following on heating with aqueous KOH, produces acetaldehyde ? (2009)
1) CH₃ COCl                 2) CH₃CH₂Cl
3) CH₂Cl CH₂Cl           4) CH₃CHCl₂
Ans.

Ans.(2) Hydride transfer is the slowest step.

28.From Amongst the following alcohols the one that would react fastest with conc.HCl and anhydrous ZnCl₂, is (2010)
1)2- Butanol
2)2- Methylpropan-2-ol
3)2-Methylpropanaol
4) 1-Butanol
Ans.(2) 3° alcohols react fastest with ZnCl₂/conc. HC1 due to formation of 3° carbocation. 2-Methylpropan-2-ol is the only 3° alcohol

Ans.

30.Silver Mirror test is given by which one of the following compounds ?                 (2011)
1) Formaldehyde          2) Benzophenone
3) Acetaldehyde           4) Acetone
Ans.

31. Trichloroacetaldehyde was subjected to Cannizzaro’s reaction by using NaOH. The mixture of the products contains sodium trichloroacetate and another compound. The other compound is     (2011)
1)2,2,2-Trichloropropanol
2)Chloroform
3)2,2,2-TrichIoroethanol
4)Trichloromethanol
Ans.

32.The strongest acid amongest the following compounds is    (2011)
1)CH₃CH₂CH(CZ)C0₂H
2)ClCH₂CH₂CH₂ COOH
3)CH3COOH
4) HCOOH
Ans.

33.Sodium ethoxide has reacted with ethanoyl chloride. The compound that is produced in the above reaction is         (2011)
1) Ethyl chloride            2) Ethyl ethanoate
3) Diethyl ether              4) 2 – Butanone
Ans.

34.Which of the following reagents may be used to distinguish between phenol and benzoic acid?           (2011)
1) Molisch reagent         2) Neutral FeCl₃
3) Aqueous NaOH         4) Tollen’s reagent
Ans.

35. Iodofrom can be prepared from all except (2012)
1) Ethyl methyl ketone 2) Isopropy alcohol
3)3-Methyl-2-butanone
4)Isobuty alcohol
Ans.

36.In the given transformation, which of the following is the most appropriate reagent ?          (2012)

Ans.

37.Arrange the following compounds in order of  decreasing acidity  (2013)

Ans.

38.Compound(A), C₈H₉Br, gives white precipate when warmed with alcoholic AgN0₃. Oxidation of (A) gives an acid (B), C₈H₆0₄. (B) easily forms anhydride on heating. Identify the compound (A).      (2013)

Ans.

39.An organic compound A upon reaction NH₃ gives B. On heatinmg B gives C. C in presence of KOH reacts with Br₂ to give CH₃CH₂NH₂ A is     (2013)

Ans.

40.An unknown alcohol is treated with the “Lucas reagent” to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism (2013)
1)secondary alcohol by S_N1
2)tertiary alcohol by S_N1
3)secondary alcohol by S_N2
4)tertiary alcohol by S_N2
Ans.

41.Sodium phenoxide when heated with C0₂ under pressure at 125°C yields a product which on a acetylation produces C.

Ans.

42.The most suitable reagent for the conversion of R – CH₂ – OH -> R – CHO is (2014)
1)PCC (Pyridinium Chlorochromate)
2)KMn0₄
3)K₂Cr₂0₇
4) Cr0₃
Ans.(1) Most suitable reagent for the conversion of 1° alcohol to aldehyde is “PCC”.

Ans.

Ans.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry  Elements of  p-Block: Groups 13,14,15,16,17 and 18

1.When H₂S is passed through Hg₂S we get(2002)
(1)HgS        2) HgS + Hg₂S
3) Hg₂S          4) Hg₂S₂
Ans.

2.Alum helps in purifying water by (2002)
(1)forming Si complex with clay particles
(2)sulphate part which combines with the dirt and removes it
(3)coagulating the mud particles
(4)making mud water soluble
Ans.(3) Alum fumisheds Al³⁺ ions which bring about coagulation of negatively charged clay poarticles bacteria etc.

3.In case of nitrogen, NC1₃ is possible but not NC1_S while in case of phosphorous, PC1₃ as well as PC1₅ are possible. It is due to (2002)
(1)availability of vacant d orbitals in P but not inN
(2)lower electronegativity of P than N
(3)lower tendency of H-bond formation in P than N
(4)occurrence of P in solid while N in gaseous state at room temperature
Ans.(1) ₇N² =ls²2s²3p³, ₁₅P = 1 s²2s²2p⁶3s²3p³ In phosphorous the 3d – orbitals are available

4.Number of sigma bonds in P₄O₁₀ is (2003)
(1)6  2) 1            3) 17            4) 16 Ans.
Ans.

5.What’happens when phosphine gas is mixed with chlorine gas ?    (2003)
(1)PC1₃ an HC1 are formed and the mixture warms up
(2)PC1₅ and HC1 are formed and the mixture cools down
(3)PH₃.C1₂ is formed with warming up
(4)The mixture only cools down
Ans.

6.Graphite is a soft solid lubricant extremely difficult to melt. The reasong for this anomalous behavior is that graphite. (2003)
(1)is an alio tropic form of diamond
(2)has molecules of variable molecular masses like polymers
(3)has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.
(4)is a non-crystalline substance.
Ans.(1) 4HC/ + 0_2–> 2Cl₂ + 2H₂0  cloud of white fumes.

7.Concentrated hydrochloric acid when kept in open air sometimes produces a cloud of white fumes. The explanation for it is that (2003)
(1)oxygen in air reacts with the emitted HC1 gas to form a cloud of chlorine gas
(2)Strong affinity of HC1 gas for moisture in air results in forming of droplets of liquid solution which appears like a cloudy smoke.
(3)due to strong affinity for water. Concentrated hydrochloric acid pulls moisture of air towards itself. This moisture forms droplets of water and hence the cloud.
(4)concentrated hydrochloric acid emits strongly smelling HC1 gas all the time.
Ans.(3) Layers are held together.

8.Glass is a (2003)
(1)super -cooled liquid 2) gel
(3)polymeric mixture
(4)micro-crystalline solid
Ans.(1) Glass is a transparent or translucent super cooled liquid.

9.For making good quality mirrors plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be    (2003)
(1)tin           2) sodium
3) magnesium               4) mercury
Ans.(4) It is because mercury exists as liquid at room temperature.

10.Which among the following factors is the mostimportant in making fluorine the strongest oxidizing halogen?(2004)
(1)Electron affinity
(2)Bond dissociation energy
(3)Hydration enthalpy 4) Ionization enthalpy
Ans.(2) Lower dissociation energy of bonds in F₂.

11.Which one the following statement regarding helium is incorrect ?   (2004)
(1) It is used to fill gas balloons instead of H₂because it is lighter and non-inflammable
(2)It is used in gas-cooled nuclear reactors
(3)It is used to produce and sustain powerful superconducting reagents (4)It is used as cryogenic agent for carrying out experiments at low temperatures
Ans.(1) Hydrogen is lightest and is non inflamable.

Ans.(4) Hydrated and coordinated aluminium cation is farmed

13.The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey powder. This transforma­tion is related to(2004)
(1)an interaction with nitrogen of the air at very low temperatures
(2)an interaction with water vapour contained in the humid air
(3)a change in the partial pressure of oxygen in the air
(4)a change in the crystalline structure of tin
Ans.(4) Transformation of crystal structure.

14.The number of hydrogen atom(s) attached to phosphorus atom in hypophosphorous acid is
(2005)
(1)zero 2) two 3) one 4) three
Ans.

15.The correct order of the thermal stability ofhydrogen halides (H – X) is                  (2005)
(1)HI > HBr > HC1 > HF
(2)HF > HC1 > HBr > HI
(3)HC1 < HF > HBr < HI
(4)HI > HC1 < HF < HBr
Ans.(2) HF is most stable.

16.Heating an aqueous solution of aluminiumchloride to dryness will give                (2005)
(1)A1C1₃ 2) A1₂C1₆
3) A1₂0₃    4) Al(OH)CI₂
Ans.

17.In silicon dioxide (2005)
(1)Each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms
(2)Each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms
(3)Silicon atoms is bonded to two oxygen atoms
(4)There are double bonds between silicon and oxygen atoms
Ans.

18.The structure of diborane (B₂H_fi) contains(2005)
(1)four 2c-2e bonds and two 3c-2e bonds
(2)two 2c-2e bonds and four 3c-2e bonds
(3)two 2c-2e bonds and two 3c-3e bonds
(4)four 2c-2e bonds and four 3c-2e bonds
Ans.

19.Which of the following chemical reactions depicts the oxidizing behaviour of H₂S0₄ ?
(1)2HI + H₂S0₄ -> I₂ + S0₂ + 2H₂0 (2006)
(2)Ca(OH)₂ + H₂S0₄ CaS0₄ + 2H₂0
(3)NaCl + H₂S0₄ NaHS0₄ + HC1
(4)2PC1_S + H₂S0₄ 2POCl₃ + 2HC1 + S0₂C1₂
Ans.

20.A metal, M forms chlorides in its +2 and 44 oxidation states. Which of the following statements about these chlorides is correct ?
(1)MC1₂ is more volatile than MC1₄ (2006)
(2)MC1₂ is more soluble in anhydrous ethanol than MC1₄
(3)MC1₂ is more ionic than MC1₄
(4)MC1₂ is more easily hydrolysed than MC1₄
Ans.

21.Which of the following statements is true ?
(1)H3PO3 is a stronger acid than H₂S0₃ (2006)
(2)In aqueous medium HF is a stronger acid than HC1
(3)HC10₄ is a weaker acid than HC10₃
(4)HNO3 is a stronger acid than HN0₂
Ans.

22.What products are expected from the disproportionation reaction of hypochlorous acid ?     (2006)
(1)HCIO3 and C1₂0 2) HC10₂ and HC10₄
3) HC1 and C1₂0           4) HC1 and HC10₃
Ans.

23.The decreasing values of bond angles from NH₃ (106°) to SbH₃ (101°) down group-15 of the periodic table is due to        (2006)
(!)increasing bp-bp repulsion
(2)increasing p-orbital character in sp³
(3)decreasing lp-bp repulsion
(4)decreasing electronegativity
Ans.(4) Repulsions will be less with lower electronagativity.

Ans.

Ans.

26.Identify the incorrect statement among the fol­lowing (2007)
(1)Ozone reacts with S0₂ to give S0₃
(2)Silicon reacts with aqueous NaOH in the presence of air to give NajS^ and H₂0
(3)Cl₂ reacts with excess of NH₃ to give N₂ and HC1
(4)Br₂ reacts with hot and strong NaOH solu­tion to give NaBr, NaBr0₄ and H₂0
Ans.

Ans.

28.Which one of the following is the correct statement ?          (2008)
(1)Boric acid is a protonic acid
(2)Beryllium exhibits coordination number of six.
(3)Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
(4)B₂H₆.2NH₃ is known as ‘inorganic benzene’.
Ans.

29.In which of the following arrangements, the e sequence is not strictly according to the property written against it ?      (2009)
(1)C0₂ < Si0₂ < Sn0₂ < Pb0₂ : increasing oxidising power
(2)HF < HC1 < HBr < HI : increasing acid strength
(3)NH₃ < PH₃ AsH₃ < SbHj : increasing basic strength
(4)B<C<0<N: increasing first ionization enthalpy
Ans.

Ans.(1) Xe0₃ is more stable than XeF₆. All the remaining reactions are feasible

Ans.

Ans.

33.Which of the following statements regarding sulphur is incorrect ?                           (2011)
(1)At 600°C the gas mainly consists of S₂ molecules
(2)The oxidation state of sulphur is never less than + 4 in its compounds
(3)S, molecule is paramagnetic
(4)The vapour at 200°C consists mostly of S₈ rings
Ans.(2) Sulphur can exhibit – 2, + 2, + 1 oxidation states also.

Ans.(3) Stability of VA group hybrides decreases from NH₃ to BiH₃ due to the decrease in M – H bond energy.
NH₃ > PH₃ > AsH₃ > SbH₃ > BiH₃
35.Which of the following on thermal decomposition yields a basic as well as an acidic oxide ?          (2012)
1) NaN0₃                      2) KC10₃
3) CaC0₃                       4) NH₄N0₃
Ans.

Ans.(1) ONF and ONO^– are isoelectronic ON Cl and ONS^– are isoelectronic

37.Which one of the following properties is not shown by NO ?                                     (2014)
(1)It’s bond order is 2.5 .
(2)It is diamagnetic in gaseous state
(3)It is a neutral oxide
(4)It combines with oxygen to form nitrogen dioxide
Ans.(2) NO is paramagnetic.

38.Among the following oxoacids, the correct decreasing order of acid strength is (2014)
(1)HC10₂ > HC10₄ > HCIO, > HOC1
(2)HCIO > HC10₂ > HCIO3 > HOCl₄
(3)HC10₄ > HCIO > HC10₂ > HOCl₃
(4)HC10₂ > HCIO3 > HC10₂ > HOC1
Ans.(4) With an increase in unprotonated oxygen atoms, acidic strength increases.

39.In the context of the Hall-Heroult process for the extration of Al, which of the following statements is false? (2015)
(1)CO and C0₂ are produced in this process
(2)A/₂0₃ is mixed with CaF₂ which lowers the melting point of the mixture and brings conductivity
(3)A/³⁺ is reduced at the cathode to form Al
(4)Na₃A/F₆ is serves as the electrolyte
Ans.[4] A/₂0₃ is dissolved in cryolite which serves as electrolyte in molten state.

40.Which among the following is the most reactive ?               (2015)
1) C/₂      2) Br₂    3) I₂ 4) ICI
Ans.[4] Interhalogen compounds are polar and are more reactive.

41.Which one has the highest boiling point ?(2015)
(1) He 2) Ne 3) Kr (4) Xe
Ans.[4] Boiling point increases with an increase in Molecular mass.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry  Elements of S-Block : Hydrogen,Group 1 and 2

1.K0₂(potassium super oxide) is used in oxygen cylinders in space and submarines. This is because it        (2002)
(1)absorbs C0₂ and increases 0₂ content
(2)eliminates moisture
(3)absorbs C0₂ 4) produces ozone
Ans.(2) 2KO, + 2H₂0 —>2KOH + H₂0₂ + 0₂. Eliminates moisture.

2.A metal M readily forms its sulphate MS0₄which is water soluble. It forms its oxide MO which becomes inert on heating. It forms an insoluble hydroxide M(OH)₂ which is soluble in NaOH solution. Then M is     (2002)
(1)Mg 2) Ba 3) Ca 4) Be
Ans.(4) Beryllium shows anomalous properties with alkaline earth metals, due to its small size.

3.In curing cement plasters water is sprinkled from time to time. This helps in           (2003)
(1)developing interlocking needle-like crystals of hydrated silicates.
(2)hydrating sand and gravel mixed with cement
(3)converting sand into silicic acid
(4)keeping it cool
Ans.(1) Cross links are developed during hydration of calcium aluminosilicates.

4.The substance not likely to contain CaC0₃ is
(1)calcined gypsum 2) sea shells (2003) 3) dolomite 4) a marble statue
Ans.(1) The composition of gypsum is CaS0₄. 2H₂0, while others are carbonates.

5.The solubilities of carbonates decrease down the magnesium group. This is due to a decrease in
(1)hydration energies of cations (2003)
(2)inter – ionic attraction
(3)entropy of solution formation
(4)lattice energies of solids
Ans.(1) The solubility is governed by AH _soIution
AH solution^– AH_lattjce_ AH_Hydration.
Due to increase in size, the magnitude of hydration energy decreases and hence the solubility.

6.Several blocks of magnesium are fixed to the bottom of a ship to          (2003)
(1)make the ship lighter
(2)prevent action of water and salt
(3)prevent puncturing by under-sea rocks
(4)keep away the sharks
Ans.(2) Magnesium provides cathodic protection and prevent rusting or corrosion.

7.Which one of the following processes willproduce hard water ?      (2003)
(1)Saturation of water with MgCO_a
(2)Saturation of water with CaS0₄
(3)Addition of Na₂S0₄ to water
(4)Saturation of water with CaC0₃
Ans.(2) Permanent hardness of water is due to chlorides and sulphates of calcium and magnesium.

8.In hydrogen – oxygen fuel cell, combustion of hydrogen occurs to      (2004)
(1)generate heat
(2)remove adsorbed oxygen from electrode surfaces
(3)produce high purity water
(4)create potential difference between the two electrodes Ans.(4) Heat is converted directlyto electricity.
Ans.(4) Heat is converted directlyto electricity.

9.One mole of magnesium nitride on the reaction with an excess of water gives (2004)
(1)one mole of ammonia
(2)two moles of nitric acid
(3)two moles of ammonia
(4)one mole of nitric acid
Ans.(3) Mg₃N₂ +6H₂0——– » 3Mg(OH)₂ + 2NH₃

10.Hydrogen bomb is based on the principle of
(1)Nuclear fission (2005)
(2) Natural radioactivity
(3) Nuclear fusion
(4)Artificial radioactivity
Ans.(3) Fusion of isotopes of hydrogen.

11.Based on lattice energy and other considerations which one of the following alkali metal chlorides is expected to have the highest melting point.(2005)
1) LiCl       2) NaCl       3) KC1       4) RbCl
Ans.(2) Although lattice energy of LiCl higher than NaCl, but LiCl is covalent in nature and NaCl ionic. There after, the melting point decreases as we move NaCl because the lattice energy decreases as size of alkali metal atom increases. Higher lattice energy denotes higher melting and boiling points.

12.The ionic mobility of alkali metal ions in aqueous solution is maximum for (2006)
1) K⁺   2) Rb⁺  3) Li⁺   4) Na⁺
Ans.(2) Hydrated Rb⁺ has small size.

13.In context with the industrial preparation of hydrogen from water gas (CO+H₂), Which of  the following is the correct statement ? (2008)
(1)CO and H₂ are fractionally separated using differences in their densities
(2)CO is removed by absorption in aqueous Cu₂Cl₂ solution
(3)H₂ is removed through occulsion with Pd
(4)CO is oxidised to C0₂ with steam in the presence of a catalyst followed by absorption of C0₂ in alkali
Ans.

14. Very pure hydrogen (99.9%) can be made by ’ which of the following processes ?   (2012)
(1)Reaction of methane with steam
(2)Mixing natural hydrocarbons of high molecular weight
(3) Elecrolysis of water
(4)Reaction of salt like hydrides with water
Ans.

15.The first ionization potential of Na is 5.1 eV. The value of electron gain enthalpy of Na⁺ will be (2013)
1) -2.55 eV                   2) -5.1 eV
3)-10.2 eV                    4) +2.55 eV
Ans.(2) Inisation potential of alkali metal atom and electron affinity of its monocovalent cation are same in magnitude, but with opposite signs.

16.The metal that cannot be obtained by electrolysis of an aqueous solution of its salt is       (2014)
1) Cr 2) Ag 3) Ca 4) Cu
Ans.(3) Ca canot be obtained by the electrolysis of aqueous solution of its salt.

17.In which of the following reactions H₂0₂ acts as reducing agent ?     (2014)
a.H₂0₂ + 2H⁺ + 2e- -> 2H₂0
b.H₂0₂ – 2e–> 0₂ + 2H⁺
c.H₂0₂ + 2e- -> 20H-
d.H₂0₂ + 20H- 2e- -> 0₂ + 2H₂0
1) (b), (d)    2) (a), (b)      3) (c), (d)    4) (a), (c)
Ans.(1) While acting as reducing agent it gives up electrons and release oxygen gas.

Ans. 4) 2 mol of water softener require one mole of Ca²⁺

19.Form the following statements regarding H₂0₂, choose the incorrect statement (2015)
(1)It can act only as an oxidizing agent
(2)It decompose on exposure to light
(3)It has to be stored in plastic or was lined glass bottles in dark
(4)It has to be kept away form dust
Ans.(1) It is disproportionating agent.

20.Which one of the following alkaline earthmetal sulphates has its hydration enthalpy greater than its lattice enthalpy ?        (2015)
1) CaS0₄ 2) BeS0₄ 3) BaS0₄ 4) SrS0₄
Ans.(2) Among alkaline earth metal sulphates BeS0₄ and MgS0₄ are water soluble due to high hydration enthalpy of Be²⁺ and Mg²⁺.

NCERT Solutions Home Page English Hindi Maths Science SocialRD Sharma

JEE Main Previous Year Papers Questions With Solutions Chemistry Haloalkenes and Haloarenes

Ans.(2) The reaction is nucleophilic sustitution reaction.

2.On mixing a certain alkane with chlorine and irradiating it with ultraviolet light, it forms only one monochloroalkane. This alkane could  be  (2003)
1) pentane                    2) isopentane
3) neopentane             4) propane
Ans.

Ans.(1) Rate of reaction will be fastest when Z is Cl because it is a weakest base.

4.The compound  formed on heating chlorobenzene with chloral in the presence concentrated sulphuric   acid  is    (2004)
1) gammexene              2)  hexachloroethane
3) Freon                        4) DDT
Ans.(4) Dicholodiphenyl trichloroethene.

Ans.(4) Due to steric hindrance.

6.Reaction of one molecule of HBr with one molecule of 1,3-butadiene at 40°C gives predominantly         (2005)
1)3-bromobutene under kinetically controlled conditions
2)l-bromo-2-butene under thermodymically controlled conditions
3)3-bromobutene under thermodynamically controlled conditions
4)l-bromo-2-butene under kinetically controlled conditions
Ans.(2)CH₃ – CH = CH₂

7. Alkyl halides react with dialkyl copper reagents to give          (2005)
1)alkenes
2)alkyl copper halides
3)alkanes
4)alkenyl halides
Ans.(3)R₂CuLi + R’X—>R-R +R-Cu + LiX

Ans.CH₃0^– is more reactive and PhO- is least reactive.

9.Reaction of trans-2-phenyl-l bromo cyclopentane on reaction with alcoholic KOH produces.     (2006)
1)4-phenylcyclopentene
2)2-phenylcyclopentene
3)1-phenylcyclopentene
4)3-phenylcyclopentene
Ans.(4) Nucleophilic substitution of Cl^– by CN^–.

10. The structure of the major product formed in the following reaction is   (2006)

Ans.(4) According to E₂ elimination mechanism.

11.Which of the following is the correct order of decreasing SN₂ reactivity ?  (2007)
1)RCH₂x > R₃CX > R₂CHX
2)RCH₂X>R₂CHX>R₃CX
3)R₃CX >R₂CHX > RCH₂X
4)R₂CHX>R₃CX>RCH₂X
Ans.(2)More is the steric hindrance at the carbon bearing the halogen, lesser is the S_N2 reactivity.

12.The organic chloro compound, which shows complete stereochemical inversion during a S_n2 reaction, is    (2008)
1)(C₂H₅)₂CHCl            2) (CH₃)₃CCl
3) (CH₃)₂CHCl             4) CH₃Cl
Ans.(4) For S_n2 reaction, the C atom is least hindered towards the attack of nucleophile in the case of CH3Cl.

13.Consider the following bromides :

Ans.(1) S_N1 proceeds via carbocation intermediate, the most stable one forming the product faster. Hence reactivity order for A, B, C depends on stability of carbocation created

14.Phenol is heated with a solution of mixture of KBr and KBr0₃. The major product obtained in the reaction is  (2011)
1)4-Bromophenol
2)2, 4, 6-Tribromophenol
3)2-Bromophenol
4)3-Bromophenol
Ans.

15.Which branched chain isomer of the hydrocarbon with molecular mas 72u gives only one isomer of mono substituted alkyl halide ?  (2012)
1) Tertiarybutylchloride
2) Neopentane
3) Isohexane
4) Neohexane
Ans.(2) Neopentane, (CH₃)₄C, on monochlorination gives only one isomer.

16.In S_n2 reactions, the correct order of reactivity for the following compounds :

Ans.(3) Order of required reactivity :
CH₃C1 > CH₃CH₂C1 > (CH₃)₂CHC1 > (CH₃)₃CC1

17.The synthesis of alkyl fluorides is best accom­plished by (2015)
1)Free radical fluorination
2)Sandmeyer’s reaction
3)Finkelstein reaction
4)Swarts reaction
Ans.(4) R -X + AgF —> R – F + AgX.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry Basic Concepts and Stoichiometry

Multlple Choice with ONE correct answer
1.In the formula X = 3YZ², X and Z have dimensions of capacitance and magnetic induction respectively. What are the dimensions of Y in MKSQ system ?     [1995-2 marks]

Ans.

Ans.

Ans.

4.A cube has a side of length 2 x 10^-2m. Calculate its volume.     [2003-2 marks]

Ans.

Ans.

6.A wire of length 1 = 6±0.06 cm and radius r = 0.5 ± 0.005 cm and mass m = 0.3 ± 0.003 g . Maximum percentage error in density is [2004-2 marks]
a) 4      b) 2           c) 1                d) 6.8
Ans.

7.Which of the following sets have different dimensions ? [2005-2 marks]
a)Pressure, Young’s modulus, stress
b)Emf, potential difference, electric potential
c)Heat, work done, energy
d)Dipole moment, electric flux, electric field
Ans.

8.The density of a solid ball is to be determined in an experiment. The diameter of the ball is measured with a screw gauge, whose pitch is 0.5 mm and there are 50 divisions on the circular scale. The reading on the main scale is 2.5 mm and that on the circular scale is 20 divisions. If the measured mass of the ball has a relative error of 2%, the relative percentange error in the density is
a) 0.9%     b) 2.4% c) 3.1%  d) 4.2%
Ans.

Multiple Choice with ONE or  More Than ONE correct answers
9.If L,C,R represent inductance, capacitance and resistance respectively, the combinations having dimensions of frequency are [1984-2 marks]

Ans.

10.Which of the following combinations have the dimensions of time ? L,C,R represent inductance, capacitance and resistance respectively [1986-2 marks]

Ans.

11.The dimensions of the quantities in one (or more) of the following pairs are the same. Identify the pair(s)  [1986-2 marks]
a) Torque and work                              b) Angular momentum and work
c) Energy and Young’s modulus        d) Light year and wavelength
Ans.

Ans.

13.The pairs of physical quantities that have the same dimensions in (are)     [1995-2 marks]
a)Reynolds number and coefficient of friction
b)Curie and frequency of a light wave
c)Latent heat and gravitational potential
d)Planck’s constant and torque
Ans.

Ans.

15.The ST unit of inductance, the henry can be written as   [1998-2 marks]
a)weber/ampere          b)     volt-sec/amp
c) joule/(ampere)²        d) ohm-second
Ans.

Matching Type
16.Match the physical quantities given in Column 1 with dimensions expressed in terms of mass (M), length (L), time (T), and charge (Q) given in Column II

Ans.

17.Column-I gives three physical quantities. Select the appropriate units for the choices given in Column-II. Some of the physical quantities may have more than one choice correct [1990-3 marks]

Ans.

18.Some physical quantities are given in column I and some possible SI units in which these quantities may be expressed are given in Coulmn II. Match the physical quantities in column I with the units in Column II……………………..  [2007-6 marks]

Ans.

Subjective / Numerical integer type
19.Give the MKS units for each of the following quantities :   [1980-3 marks]
i) Young’s modulus  ii) Magnetic induction  iii) Power of a lens
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20.A gas bubble, from an explosion under water,oscillates with a period T proportional to p^ad^bE^c • Where P is the static pressure, d is the density of water and E is the total energy of the explosion. Find the   values of a,b and c            [1981-3 marks]
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21.Write the dimensions of the following in terms of mass, time, length and charge
i) magnetic flux ii) rigidity modulus [1982-2 marks]
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Fill in the blanks
22.Planck’s constant has dimensions………………. [1985-2 marks]
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23.In the formula X = 3YZ²,X and Z have dimensions of capacitance and magnetic induction respectively. The dimensions of Y in MKSQ system are………………………[1988-2 marks]
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24.The dimensions of electrical conductivity is…………………..  [1997-1 mark]
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JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry Alkanes ,Alkenes ,Alkynes and Arenes

1.Which of these will not react with acetylene ?(2002)
1) NaOH                                 2)  Ammonical  AgB0₃
3) Na                                        4) HCl
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2.What is the product when acetylene reacts with hypochlorous acid ?    (2002)
1) CH3COCI                         2)   C1CH₂CH0
3) Cl₂CHCHO                        4)  C1CHCOOH
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3.Bottles containing C₆H₅I and C₆H_SCH₂I lost their original tables. They were labelled A and B for testing. A and B were separately taken in test tubes and boiled with NaOH solution. The end solution in each tube was made acidic with dilute HNO_a and then some AgN0₃ solution was added. Substance B gave a yellow’ precipitate. Which one of the following statements is true for this experiment? (2003)
1)AandC₆H₅CH₂I
2)B and C₆H₅I
3)Addition of HN0₃ was unnecessary
4) A was C₆H₅I
Ans.(4) C₆H₅I will not respond to silver nitrate test because C-I bond has a partial double bond character.

4. Butene-1 may be converted to butane by reaction with (2003)
1) Sn-HCl                  2) Zn-Hg
3) Pd /H₂                     4) Zn- HCl
Ans.(3) Hydrogenation.

5.Which one of the following has the minimum boiling point ?   (2004)
1) n-butane                                                2)  isobutane
3) 1-butene                                               4) 1-butyne
Ans.(2) Lower van der Waals forces.

6.Which one of the following reduced with zinc and hydrochloric acid to give the  corresponding hydrocarbon  ?   (2004)
1) Ethyl acetate                     2) Butan-2-one
3) Acetamide                         4) Acetic acid
Ans.(2) Total reduction of carbonyl.

7.2 methylbutane on reacting with bromine in the presence of sunlight gives mainly (2005)
1)1- bromo -2 – methylbutane
2)2 – bromo -2 – methylbutane
3)2- bromo -3 – methylbutane
4)1 – bromo -3 – methylbutane
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8.Acid catalyzed hydration of alkenes except ethene leads to the formation of (2005)
1)Primary alcohol
2)Secondary or tertiary alcohol
3)Mixture of primary and secondary alcohols
4)Mixture of secondary and tertiary alcohols
Ans.(4) concept of hydration.

Ans.(1) Conjugated acid of Cl^– is a stronger acid. The acid is HCl.

10.Elimination of bromine from 2-bromobutane results in the formation of-       (2005)
1)Equimolar mixture of 1 and 2-butene
2)Predominantly 2-butene
3)Predominantly 1-butene
4)Predominantly 2-butyne
Ans.(2) Saytzeff’s product.

11.HBr reacts with CH₂ = CH – OCH₃ under anhydrous conditions at room temperature to give
1)CH₃CHO and CH₃Br
2)BrCH₂CHO and CH₃OH
3)BrCH₂ – CH₂ – OCH₃
4)H₃C – CHBr – OCH₃
Ans.(4) Electrophilic addition reaction is more favourable.

Ans.(2) Ethylene

13.Which of the following reactions will yield 2, 2-dibromopropane ?    (2007)
1)CH₃ – C = CH + 2HBr —>
2)CH₃CH = CHBr + HBr ->
3)CH = CH + 2HBr —>
4)CH₃ – CH = CH₂ + HBr ->
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14.The reaction of toluene with Cl₂ in presence of FeCl₃ gives predominantly       (2007)
1)benzoyl chloride
2)benzyl chloride
3)o-and p-chlorotoluene
4)m-chlorotoluene
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15.Presence of a nitro group in a benzene ring (2007)
1)activates the ring towards electrophilic substitution
2)renders the ring basic .
3)deactivates the ring towards nucleophilic substitution
4)deactivates the ring towards electrophilic substitution
Ans.(4) -N0₂ group shows -M effect. It withdraws the electron density from the ring and hence deactivate the ring towards electrophilic aro­matic substitution.

16.In the following sequence of reactions, the alkene affords the compound ‘B’

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Ans.(2) – N0₂ is electron withdrawing which will destabilize a-complex.

18.The hydrocarbon which can react with sodium in liquid ammonia is (2008)
1)CH₃CH₂CH₂C=CCH₂CH₂CH₃
2)CH₃CH₂C =CH .
3)CH₃CH = CHCH₃
4)CH₃CH₂C =CCH₂CH₃
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19.The treatment of CH₃MgX with CH₃OC-H produces (2008)

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20.One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44u. The alkene is               (2010)
1)propene   2) 1-butene   3) 2-butene  4) ethene
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21.Ozonolysis of an organic compound gives formaldehyde as one of the products. This confirms the presence  of :          (2011)
1)an isopropyl group
2)an acetylenic triple bond
3)two ethylenic double bonds
4)a vinyl group
Ans.(4) Ozonolysis of an organic compound give formaldehyde when it containing atleast one vinylic double bond. HjC = CH – R.

22.2-Hexyne gives trans-2-hexene on treatment with  (2012)
1) Pt/H₂                                    2)    Li / NH₃
3) Pd / BaS0₄                          4)      LiAlH₄
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23.The major organic compound formed by the reaction of 1,1,1 – trichloroethane with silver powder is              (2014)
1) 2-Butene                             2) Acetylene
3) Ethene                                 4)   2-Butyne
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24.Which compound would give 5-keto-2-methyl hexanal upon ozonlysis ?

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JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Maths Statistics and Probatility

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JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Maths Trignometry

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JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry Atomic Structure and Electronic Configuration

1.In a hydrogen atom, if energy of an electron in the ground state is 13.6 eV, then that in the 2nd excited state is                (2002)
1) 1.51 eV 2) 3.4 eV 3) 6.04 eV 4)13.6 eV
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2.

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3.Which of the following ions has the maximum magnetic moment.                               (2002)
1) Mn⁺² 2) Fe⁺² 3) Ti⁺² 4) Cr⁺²
Ans.(1) Mn²⁺ has the maximum number of unpaired electrons (5) and therefore has maximum moment

4.The number of d-electrons retained in Fe²⁺ (At.no. of Fe = 26) ion is                          (2003)
1) 4                 2) 5                   3) 6                   4) 3
Ans.(3) Configuration of Fe⁺² = 3d⁶.4s°

5.

Ans.(1) For s-electron, l = 0; Angular momentum=zero

6.In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen        (2003)
1) 5 —» 2        2)4 —>1       3) 2—>5          4) 3->2
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7.

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8.

Ans.(3) For 4f orbital, n= 4 and 1 = 3. Values of m = -3, -2, -1,0, +1, +2, +3. Combination of 1 = 3 m = +1 is the only acceptable option.

9.Consider the ground state of Cr atom (Z=24).The number of ■electrons with the azimuthal quantum numbers 1 =1 and 2 are respectively
1)12 and 4      2)  16 and 5                (2004)
3) 16 and 4     4) 12 and 5
Ans.(4) Configuration of Cr (Z = 24) is ls²2s²2p⁶3s²3p⁶3d⁵4s*
1=1, denotes p-electrons (2p⁶, 3p⁶)
1 = 2,’denotes d-electrons (3d⁵)

10.

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Ans.(2) Like +7 state for Mn

12.In a multi-electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic and electric fields?(2005)
(a) n = 1,1 = 0, m = 0 (b) n = 2,1 = 0, m = 0
(c) n = 2,1 = 1, m = 1 (d) n = 3,1 = 2, m = 1 (e) n = 3,1 = 2, m = 0
1)  (a) and (b)         2) (b) and (c)
3)  (c) and (d)       4) (d) and (e)
Ans.(4) n is same and orbital is 3d.

13.Which of the following statements in relation to the hydrogen atom is correct ?   (2005)
(1)3s orbital is    lower   in  energy than 3p      orbital
(2)3p orbital is lower   in  energy than 3d       orbital
(3)3s and 3p orbitals are of lower energy than 3d orbital
(4)3s, 3p and 3d orbitals all have the same energy
Ans.4) Auf-bau principle is not applicable for H atom

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16.The “spin-only” magnetic moment [in units of Bohr magneton] of Ni²⁺ in aqueous solution would be (Atomic number of Ni = 28) (2006)
1) 2.84       2) 4.9   3) 0         4) 1.73
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17.Which of the following sets of quantum numbers represents the highest energy of an atom ? (2007)
(1)n=3, 1=2, m=l, s=+l/2
(2)n=3, 1=2, m=l, s=+l/2
(3)n=4, 1=0, m=0, s=+l/2
(4)n=3, 1=0, m=0, s= +1/2
Ans.(2) Maximum value of (n +1) denotes high­est energy of the orbital.

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23.A gas absorbs a photon of 355 nm and emits
at two wavelengths. It one of the emissions is at 680 nm, the other is at     (2011)
1) 743             2)     518         3)  1035 4) 325 nm
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24.The electrons identified by quantum numbers n and l               (2012)
a) n = 4, / = 1 b) n   = 4, l   = 0
c) n = 3, l = 2 d) n   = 3, /  = 1
can be placed in order of increasing energy as
l)c<d<b<a        2)d<b<c<a
3)b<d<a<a       4)a<c<b<d
Ans.(2) Greater the (n + /) value, greater is the energy. If (n + l) values are equal, then greater the ‘n’ value greater is the energy.

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Ans.(2) 5s¹ configuration of valence electron.

27.Which of the following is the energy of a possible excited state of a possible excited state of hydrogen?       (2015)
1) +13.6 eV                             2) -6.89 eV
3) -3.4 eV                                4) +6.8 eV
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