Entrance Exam – Page 11

JEE Main Mathematics Vectors Previous Year Questions with Solutions

December 3, 2022

JEE Main Previous Year Papers Questions With Solutions Maths Vectors

Ans.

JEE Main Previous Year Papers Questions With Solutions Chemistry Periodic Classification and Properties

December 3, 2022

JEE Main Previous Year Papers Questions With Solutions Chemistry Periodic Classification and Properties

1.Which is the correct order of ionic sizes ?(2002)
(1)Ce > Sn > Yb > Lu 2) Sn > Ce > Cu > Yb
3) Lu > Yb > Sn > Ce 4) Sn > Yb > Ce > Lu
Ans.(1) Size decrease as Z increases.

2.The radhis of La³⁺ (Atomic number of La=57) is 1.06A. Which one of the following given values will be closest to the radius of Lu³⁺ (Atomic number of Lu = 71)? (2003)
(1)40 A 2) 1.06 A
3) 0.85 A 4) 1.60 A
Ans.

3.According to the Periodic Law of elements, the variation in properties of elements is related to their. (2003)
(1)nuclear masses
(2) atomic numbers
(3)nuclear neutron-proton number ratios
(4)atomic masses
Ans.(2)The properties of elements change with a change in atomic number

4.Which one of the following is an amphoteric oxide? (2003)
(1)Na₂0 2) S0₂ 3)B₂0₃ 4) ZnO
Ans.(4) ZnO reacts with HC/ and NaOH

5.The atomic numbers of vanadium (V),Chromium (Cr), manganese (Mn) and iron (Fe) are respectively 23, 24, 25 and 26. Which one of these may be expected to have the highest second ionization enthalpy ? (2003)
(1)C r 2) Mn 3) Fe 4) V
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Ans.(1)18 electrons each.

8.Among A1₂0₃, Si0₂, P₂0₃ and S0₂ the correct order of acid strength is (2004)(1)S0₂ < P₂0₃ < Si0₂ < A1₂0₃
(2)A1₂0₃ < Si0₂ < P₂0₃ < S0₂
(3)A1₂0₃ < Si0₂ < S0₂ < P₂0₃
(4)Si0₂ < S0₂ < A1₂0₃ < P₂0₃
Ans.(2)Al, Si, P, S. Acidity of oxides increases with increase in non-metallic character.

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10.Beryllium and aluminium exhibit many properties which are similar. But the two elements differ in (2004)
(1)exhibiting maximum covalency in compound
(2)exhibiting amphoteric nature in their oxides
(3)forming covalent halides
(4)forming polymeric hydrides
Ans. (1)Be and Al have diagonal relationship. They possess similar properties but Be cannot form they polymeric hydrides.

11.Which of the following oxides is amphoteric in character ? (2005)
(1)CaO 2) C0₂ 3) Si0₂ 4) Sn0₂
Ans.

12.The lanthanide contraction is responsible for the fact that (2005)
(1)and Y have about the same radius
(2)Zr and Nb have similar oxidation state
(3)Zr and Hf have about the same radius
(4)Zr and Zn have the same oxidation
Ans.(3) Due to Lanthanide contraction.

13.In which of the following arrangements the order is NOT according to the property indicated against it ? (2005)
(1)Al³⁺ < Mg²⁺ < Na⁺ < F”
‘ Increasing ionic size
(2)B<C<N<0 ‘
Increasing first ionization enthalpy
(3)I < Br < F < Cl
Increasing electron gain enthalpy
(4)Li < Na < K < Rb Increasing metallic radius
Ans.(2) Ionisation energy of N is more (p³ config) B < C < O < N

14..Which of the following factors may be regarded as the main cause of lanthanide contraction ?(2005)
(1)Poor shielding of one of 4f electron by another in the subshell
(2)Effective shielding of one of 4f electrons by another in the subshell
(3)Poorer shielding of 5d electrons by 4f electrons
(4)Greater shielding of 5d electrons by 4f electrons
Ans.(1) Poor shielding of f electrons.

15.Which one of the following sets of ions represents a collection of isoelectronic species? (2006)
1) K⁺ , Cl”, Ca²⁺, Sc³⁺ 2) Ba²⁺, Sr²⁺, K⁺, S²“
3) N³-, O²-, F”, S²– 4) Li⁺, Na⁺, Mg²⁺, Ca²⁺
Ans.(1) Each species with 18 electrons

16.The increasing order of the first ionization enthalpies of the elements B, P, S and F (lowest first) is            (2006)
1)F<S<P<B        2)P<S<B<F
3)B<P<S<F        4)B<S<P<F
Ans.(4) B has lone p’ electron.

17.Following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens are given. Which of these statements gives the correct picture?(2006)
(1)The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic nu’mber down the group
(2)In both the alkali metals and the halogens the chemical reactivity decreases with increase in atomic number down the group
(3)Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens
(4)In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group
Ans.(4) Most reactive metal is Cs and most reactive non metal is F.

18.The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizinig order of the polarizing power of the cationic species, K⁺, Ca²⁺, Mg²⁺, Be²⁺ ? (2007)
(1)Mg²⁺,Be²⁺,K⁺,Ca²⁺
(2)Be²⁺, K⁺, Ca²⁺, Mg²⁺
(3)K⁺,Ca²⁺,Mg²⁺,Be²⁺
(4)Ca²⁺,Mg²⁺,Be²⁺,K⁺
Ans.(3) Higher the charge / size ratio, more is the polarizing power.

19.The set representing the correct order of ionic radius is : (2009)
(1)Li⁺ > Be²⁺ > Na⁺ > Mg²⁺
(2)Na⁺ > Li⁺ > Mg²⁺> Be²⁺
(3)Li⁺ > Na⁺ > Mg²⁺ > Be²⁺
(4)Mg²⁺ > Be²⁺ > Li⁺ > Na⁺
Ans.(2) Follow the periodic trends of ionic radii

20.The correct order of radii is (2010)
(1)Al³⁺ > Mg²⁺ > Na⁺ > F- > O²–
(2)Na⁺ > Mg²⁺ > Al³⁺ > O²– > F^–
(3)Na⁺ > F- > Mg²⁺ > O²– > Al³⁺
(4)O²– > F- > Na⁺ > Mg²⁺ > Al³⁺
Ans.

21.Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides ? (2011)
(1)IS^O < I^O < MgO < A/₂0₃
(2)I^O < Na₂0 < A/₂0₃ < MgO
(3)A/₂0₃ < MgO < NajO < K^O
(4)MgO < K^O < AZ₂0₃ < Na₂0
Ans.(3) As electropositive character increases basic nature metal oxides increases
A/₂0₃< MgO < Na_zO < K₂0

22.Iron exhibits +2 and +3 oxidation states.Which of the following statements about iron is incorrect ? (2012)
(1)Ferrous oxide is more basic in nature than the ferric oxide
(2)Ferous compounds are relatively more ionic than the corresponding ferric compounds
(3)Ferrous compounds are less volatile than the corresponding ferric compounds
(4)Ferrous compounds are more easily hydrolysed than the corresponding ferric compounds
Ans.(4) With increasing the oxidation state, acidic strength increases. Basic strength : FeO > Fe₂0₃With increasing the positive charge of cation, ionic nature decreases. Thus ferrous compounds are more ionic than ferric compounds.Ferrous compounds are less easily hydrolysed than ferric compounds.

Ans.

24.Which of the following represents the correct ‘ order of increasing first ionization enthalpy for Ca, Ba, S, Se and Ar ? (2013)
(1)Ca< S < Ba < Se < Ar
(2)S < Se < Ca < Ba < Ar
(3)Ba < Ca < Se < S < Ar
(4)Ca < Ba < S < Se < Ar
Ans.(3) First ionisation enthalpy is highest for Ar. Least for Ba

25.The ionic radii (in ) of N respectively
(1)36, 1.40 and 1.71
(2)36, 1.71 and 1.40
(3)71, 1.40 and 1.36
(4)71 and 1.36 and 1.40
Ans.[3] N-³ > CL² > FIn isoelectronic series size decreases as increases.

JEE Main Home Maths Physics Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry States of Matter: Gases,Liquids and Solids

December 3, 2022

JEE Main Previous Year Papers Questions With Solutions Chemistry States of Matter: Gases,Liquids and Solids

Ans. (3) PV = nRT
Number of moles per litre = n /V Therefore, n / V = P / RT.

2.

Ans.

3. Kinetic theory of gases proves (2002)
(1)only Boyle’s law
(2)only Charles’ law
(3)only Avogadro’s law
( 4) all of these
Ans.(4)Postulates of kinetic theory explains all gas laws.

4. The heat required to raise the temperature of body by 1 K is called (2002)
1) specific heat 2) thermal capacity
3) water equivalent 4) none of these
Ans.(2)The heat required to raise the temperature of body by IK is called thermal capacity or heat capacity.

5.Na and Mg crystallize in BCC and FCC type crystals respectively. Then the number of atoms of Na and Mg present in the unit cell of their respective crystal is        (2002)
1)4 and 2                        2) 9 and 14
3) 14 and 9                     4) 2 and 4
Ans.

6.How many unit cells are present in a cubeshaped ideal crystal of NaCl of mass 1.00 g ? [Atomic masses : Na = 23, Cl = 35.5] (2003)
1) 5.14 x 10²¹ unit cell 2) 1.28 x 10²¹ unit cell
3) 1.71 x 10²¹ unit cell 4) 2.57 x 10²¹ unit cell
Ans.

7. According to the kinetic theory of gases, in an ideal gas, between two successive collisions a gas molecule travels (2003) l
(1) in a wavy path
(2)in a straight line path
(3)with an accelerated velocity
(4)in a circular path
Ans.

8. As the temperature is raised from 20°C to 40°C, the average kinetic energy of neon atoms changes by a factor of which of the following? (2004)

Ans.

9.In Van der Waals equation of state of the gas law, the constant ‘b’ is a measure of (2004)(1)intermolecular repulsions
(2)intermolecular collisions per unit volume
(3)Volume occupied by the molecules
(4)intermolecular attraction
Ans.(3) In van der Waals equation, ‘b’ is the excluded yolume. Exculded volume is the volume occupied by the molecules of gas

Ans.(4) Few ion pairs are missing from the given lattice points.

Ans.

12.An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be (2005)
1) AB 2)A₂B 3) AB₃ 4)A₃B
Ans.

13. Which one of the following statements is NOT true about the effect of an increase in temperature on the distribution of molecular speeds in a gas ? (2005)
(1)The most probable speed increases
(2)The fraction of the molecules with the most probable speed increases
(3)The distribution becomes broader
(4)The area under the distribution curve remains the same as under the lower temperature
Ans.(2) Most probable velocity increase and fraction of molecule possessing most probable velocity decreases.

14.

Ans.

15.An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If T. is the initial temperature and T_fis the final temperature, which of the following statements is correct ? (2006)
(1)(T_f)_irrevXT_f)_rev
(2)T_f > Tj for reversible process but T_f = T_} for irreversible process
(3)(T_f)rev = (T_f)_irrev
(4)T_f = Tj for both reversible and irreversible processes
Ans.(2) Concept of workdone

Ans.

18.Copper crystallizes in fee with a unit cell length of 361 pm. What is the radius of copper atom?
1) 108pm 2) 127pm (2009)
3) 157pm 4) 181pm
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20.

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21.Percentage of free space in cubic close packed structure and in body centered packed structure are respectively   (2010)
1)30% and 26%               2) 26% and   32%
3) 32% and 48%              4) 48% and    26%
Ans.(2) packing fraction of cubic close packing and body centered packing are 0.74 and 0.68 respectively.

22.’a’ and ‘b’ are van der Waal’s constants for gases. Chlorine is more easily liquefied than ethane because (2011)
(1)a for C/₂ < a for C₂H₆ but b for Cl₂ > b forc₂h₆
(2)a for C/₂ > a for C₂H₆ but b for C/₂ < b forc₂h₆
(3)a and b for Cl₂ > a and b for C₂H_g
(4)a and b for C/₂ < a and b for C₂H₆
Ans.(2) Inter molecular forces and molecular weight is more for CZ₂ hence Cl₂ has high boiling point than C₂H₆. But the size of molecule C₂H₆ is greater than C/₂ hence for C₂H₆ b is greater than C/₂.

23.In a face centred cubic lattice, atom A occupies the corner positions and atoms B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is (2011)
1)A₂B₃ 2)A₂B₅ 3)A₂B 4)AB₂
Ans.
.

24.Lithium forms body centred cubic streture. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be (2012)
1) 75 pm 2) 300 pm 3) 240 pm 4) 152 pm
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25.The compressibility factor for a real gas at high pressure is        (2012)
1) 1+RT/Pb                     2) 1
3) 1+Pb/RT                     4) 1-Pb/RT
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26.For gaseous state, if most probable speed is ‘ denoted by C*, average speed by c and mean square speed by C, then for a large number of molecules the ratios of these speeds are
(1)C* : C : C = 225 : 1.128 : 1 (2013)
(2)C* : C : C = 1.128 : 1.225 : 1
(3)C* : C : C = 1: 1.128 : 1.225
(4)C* : C : C = 1 : 1.225 : 1.128
Ans.

27.Which of the following exists as covalent crystals in the solid state?  (2013)
1) Iodine                       2) Silicon
3) Sulphur                     4) Phosphorus
Ans.(2) I₂, P₄, S_g are molecular crystals Silicon is covert crystal

28.Experimentally it was found that a metal oxide has formula M_09g Metal M, is present as M²⁺ and M³⁺ in its oxide. Fraction of the metal which exists as M³⁺ would be (2013)
1) 7.01% 2) 4.08% 3) 6.05% 4) 5.08%
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