Solving ICSE Class 10 Chemistry Previous Year Question Papers ICSE Class 10 Chemistry Question Paper 2021 Semester 1 is the best way to boost your preparation for the board exams.
ICSE Class 10 Chemistry Question Paper 2021 Solved Semester 1
Time : 1½ hour
Maximum Marks : 40
General Instructions:
- Answers to this Paper must be written on the paper provided separately.
- You will not be allowed to write during the first 10 minutes.
- This time is to be spent in reading the question paper.
- The time given at the head of this Paper is the time allowed for writing the answers.
- Attempt all questions from Section A and any three questions from Section B.
- The marks intended for questions are given in brackets [].
SECTION – A
(Attempt all questions)
Question 1.
In the periodic Table, elements of period 3 are arranged in the increasing order of ionization potential as: [1]
(a) B, N, Cl, Ar
(b) Mg, Si, S, Ar
(c) Ar, Si, S, Mg
(d) Si, Ar, Cl, Mg
Answer:
(b) Mg, Si, S, Ar
Size of atoms decrease
Tendency to lose electrons decrease
Hence, ionization potential increase.
Question 2.
If Relative Molecular Mass of Butane (C4H10) is 58 then its vapour density will be: [1]
(a) 58
(b) 29
(c) 32
(d) 16
Answer:
(b) Molecular mass = Vapour density × 2
Vapour density = \(\frac{\text { M.M. }}{2}=\frac{58}{2}\) = 29
Question 3.
Identify one statement that holds true for electrolysis of molten lead bromide: [1]
(a) Silver grey metal deposits at the anode
(b) Temperature is not maintained during the electrolysis
(c) Brown vapours of bromine are obtained at the anode.
(d) Electrolyte contains H+ ions along with Pb2+ ions
Answer:
(c) PbBr2(M) ⇌ Pb2+(Cathode) + 2Br-1(Anode)
At anode:
Br-1 – le– → Br
Br + Br → Br2↑
[Reddish brown vapours of bromine are obtained]
Question 4.
The tendency of an atom to attract shared pair of electrons to itself when forming a chemical bond is known as: [1]
(a) Electron affinity
(b) Electronegativity
(c) Ionization potential
(d) Nuclear charge
Answer:
(b) Electronegativity: The tendency to attract shared pair of electrons towards itself.
Example:
Chlorine acquires partial negative charge due to high electronegativity.
Question 5.
Solid sodium chloride does not conduct electricity as: [1]
(a) The strength of the bond is weak
(b) It contains free ions
(c) It does not contain any free ions
(d) It contains free ions as well as molecules
Answer:
(c) (Na+)(Cl–) Solid sodium chloride does not conduct electricity as the ions are held strongly by strong electrostatic forces of attraction. It does not contain any free ions for conduction of electricity.
Question 6.
Elements A and B have electronic configurations 8 and 13 respectively. The chemical formula formed between A and B will be: [1]
(a) AB
(b) B3A3
(c) A2B3
(d) B2A3
Answer:
(d) B2A3
Question 7.
The percentage of hydrogen present in NaOH is: (Relative Molecular Mass of NaOH = 40) (At. Wt. of H = 1) [1]
(a) 2.5
(b) 25
(c) 0.25
(d) 0.025
Answer:
(a) NaOH = 23 + 16+ 1 = 40
% of hydrogen = \(\frac{\text { Mass of hydrogen }}{\text { Total weight }}\) × 100
= \(\frac{1}{40}\) × 100 = 2.5
Question 8.
A salt formed by incomplete neutralization of an acid by a base :
(a) Basic salt
(b) Acid salt
(c) Normal salt
(d) Complex salt
Answer:
(b)
Incomplete neutralization results in acid salt and complete neutralization results in normal salt.
Question 9.
The colour of the precipitate formed after the addition of a small amount of sodium hydroxide solution to an aqueous solution of ferric chloride is: [1]
(a) gelatinous white
(b) pale blue
(c) reddish brown
(d) dirty green
Answer:
(c) FeCl3 + 3NaOH → Fe(OH)3 ↓ + 3NaCl (Reddish brown precipitates)
Question 10.
Alkaline earth metals have the same:
(a) number of valence electrons
(b) number of shells
(c) metallic property
(d) ionization potential
Answer:
(a)
Question 11.
Which of the following compounds neither dissociate nor ionise in water? [1]
(a) Hydrochloric acid
(b) Sodium hydroxide
(c) Potassium Nitrate
(d) Carbon tetrachloride
Answer:
(d) All ionic compounds dissociate in water. Only covalent compounds do not dissociate as they do not form ions.
HCl ⇌ H+ + Cl–
NaOH ⇌ Na+ + OH–
KNO3 ⇌ K+ + NO–3
Question 12.
The table shows the electronic configuration of four elements. [1]
| Element | Electronic Configuration |
| W | 2, 6 |
| X | 2, 8 |
| Y | 2, 8,1 |
| Z | 2, 8,7 |
Which pair of atoms will form a covalent compound?
(a) two atoms of W
(b) two atoms of X
(c) an atom of W and an atom of X
(d) an atom of Y and an atom of Z
Answer:
(a) Two atoms of W
Question 13.
Element with an atomic number 19 will: [1]
(a) accept an electron and get oxidized
(b) accept an electron and get reduced
(c) lose an electron and get oxidized
(d) lose an electron and get reduced
Answer:
(c)
It will lose one electron and hence gets oxidized.
Question 14.
Which of the following has two sets of lone pair of electrons in them? [1]
(a) Ammonia
(b) Methane
(c) Water
(d) Ammonium ion
Answer:
(c)
Question 15.
If the empirical mass of the formula PQ2 is 10 and the Relative Molecular Mass is 30, then the molecular formula will be: [1]
(a) PQ2
(b) P3Q2
(c) P6Q2
(d) P3Q6
Answer:
(d) Empirical mass = 10
Relative molecular mass = 30
n = \(\frac{\text { R.M.M. }}{\text { E.M. }}=\frac{30}{10}\) = 3
M.F. = (E.F.)n
= (PQ2)3
= P3Q6
Question 16.
Which of the following is a tribasic acid? [1]
(a) H2SO4
(b) Al(OH)3
(c) H3PO4
(d) Ca(OH)2
Answer:
(c) H3PO4 ⇌ 3H+ + PO43-
The acid which gives three hydrogen ions to be neutralized by hydroxyl ions of base is known as tribasic acid.
Question 17.
If a solution of an electrolyte mixture has calcium ions, cupric ions, zinc ions and magnesium ions, which of these ions would you see preferentially discharged at the cathode? [1]
(a) Calcium ions
(b) Zinc ions
(c) Cupric ions
(d) Magnesium ions
Answer:
(c) The ions which are present at the bottom of reactivity series are preferentially discharged.
Question 18.
Which of the following ions will readily discharge at the anode during the electrolysis of acidulated water? [1]
(a) OH
(b) SO42-
(c) Cl–
(d) H+
Answer:
(a) OH– ions are readily discharged during electrolysis of acidulated water.
H2SO4 ⇌ 2H+ + SO42-
At anode: Both SO42- and OH– migrate, but OH– ions are discharged.
4OH– ⇌ 2H2O + O2↑
Question 19.
If the imperial formula of a compound is CH and its vapour density is 13, then its molecular formula will be: [ 1 ]
(At. Wt. C=12, H=l)
(a) CH
(b) C2H2
(c) C4H4
(d) C3H3
Answer:
(b) Empirical formula CH
Vapour density = 13
Empirical formula mass = 12 + 1 = 13
Molecular mass = 2 × VD
= 2 × 13 = 26
n = \(\frac{\text { Molecular mass }}{\text { Empirical mass }}\)
= \(\frac{26}{13}\) = 2
Molecular formula = (Empirical formula)n
= (CH)2
= C2H2
Question 20.
Aqueous solution of Cupric chloride forms a deep blue solution on addition of: [1]
(a) dropwise sodium hydroxide
(b) excess sodium hydroxide
(c) dropwise ammonium hydroxide
(d) excess ammonium hydroxide
Answer:
(d) CuCl2 + 2NH4OH → CU(OH)2↓ + 2NH4Cl
CU(OH)2 + 2NH4Cl + 2NH4OH → 4H2O + [CU(NH3)4] Cl2 (Deep blue solution) (Tetraamine copper chloride)
Question 21.
Which statement about conduction of electricity is correct? [1]
(a) Electricity is conducted in aqueous solution by electrons
(b) Electricity is conducted in a metal wire by ions
(c) Electricity is conducted in a molten electrolyte by electrons
(d) Electricity is conducted in an acid solution by ions
Answer:
(d) Acid splits to form ions and these ions are responsible for conduction of electricity.
Question 22.
If an element has low ionization potential, then it is likely to be a: [1]
(a) metal
(b) metalloid
(c) non metal
(d) inert gas
Answer:
(a) The bigger the size, easier it is to lose electrons and hence lower is the ionization potential. Since, alkali metal has big size; it has low ionization potential.
Question 23.
Which electron arrangement for the outer shell electrons in a covalent compound is correct? [1]
Answer:
(c)
Question 24.
The products formed when an acid reacts with a base is:
(a) salt and hydrogen
(b) salt and oxygen
(c) salt and water
(d) salt and carbon dioxide
Answer:
(c) Acid + Base → Salt + Water
HCl + NaOH → NaCl (Salt) + H2O (Water)
This reaction is known as neutralization reaction.
Question 25.
In the circuit below, the lamp lights up. What could X be?
(a) a solution of alcohol in water
(b) a solution of sodium chloride in water
(c) sugar solution
(d) solid potassium chloride
Answer:
(b) Only sodium chloride can form ions in water. Hence, it is the only solution that can conduct electricity.
Question 26.
Which one of the following is a non-metallic cation? [1]
(a) K+
(b) NH4+
(c) Cu2+
(d) Na+
Answer:
(b) K+, Cu2+, Na+ are all metallic ions. Only ammonium ion (NH4+) is a non metallic cation.
Question 27.
Type of bonding present in hydrogen chloride: [1]
(a) metallic
(b) ionic
(c) covalent
(d) coordinate
Answer:
(c)
Question 28.
The non-metallic properties of elements from left to right in a Periodic Table: [1]
(a) increases
(b) decreases
(c) remains same
(d) first increases and then decreases
Answer:
(a) As we move along the period, the number of valence electrons increase, the hold of nucleus increase, tendency to lose electron decrease and metallic character increase.
Question 29.
The aqueous solution that contains both ions and molecules: [1]
(a) sulphuric acid
(b) nitric acid
(c) acetic acid
(d) hydrochloric acid
Answer:
(c)
Acetic acid is a weak acid. It does not dissociate completely. Hence, it contains both ions as well as molecules.
Question 30.
The basic oxide which is an alkali: [1]
(a) Copper oxide
(b) Sodium oxide
(c) Ferric oxide
(d) Zinc oxide
Answer:
(b) The main three alkalis are sodium hydroxide, potassium hydroxide and ammonium hydroxide.
Hence, sodium oxide is the basic oxide which is an alkali.
Na2O + H2O → 2NaOH
Question 31.
If the pH of a solution is ‘2’ then solution is a: [1]
(a) strong acid
(b) strong alkali
(c) weak acid
(d) weak alkali
Answer:
(a) Lower the value of pH, more is the acidic character. Hence, a solution with pH 2 is more acidic.
Question 32.
The acidity of aluminium hydroxide is: [1]
(a) 3
(b) 1
(c) 4
(d) 2
Answer:
(a) Al(OH)3 ⇌ Al3+ + 3OH-1
Acidity is the number of hydroxyl ions furnished to be neutralised with H+ ions of an acid.
Question 33.
Hydracids are those acids which contain: [1]
(a) Hydrogen with any metal
(b) Hydrogen, a non-metal and oxygen
(c) Hydrogen and a non-metal other than oxygen
(d) Hydrogen and oxygen only
Answer:
(c) Hydracids are compounds of hydrogen and non-metals like HCl, HBr, HF, HI.
Question 34.
The oxidation reaction among the following is : [1]
(a) Fe3+ + 3e– → Fe
(b) Fe2+ – 1e– → Fe3+
(c) Cl2 + 2e– → 2Cl1-
(d) Cu2+ + 2e– → Cu
Answer:
(b)
Question 35.
A student added excess of sodium hydroxide solution to each of the salt solution. An insoluble precipitate formed was observed in: [1]
(a) Calcium nitrate
(b) Zinc nitrate
(c) Lead nitrate
(d) Sodium nitrate
Answer:
(a) Excess of sodium hydroxide leads to formation of insoluble precipitates. Only in case of calcium nitrate zinc nitrate and lead nitrate form soluble complex sodium zincate and sodium plumbate respectively. Sodium nitrate is soluble completely and excess of sodium hydroxide has no effect.
Question 36.
Which apparatus could be used to electroplate an iron nail with copper? [1]
Answer:
(a) The article to be electroplated is always made cathode. The electrolyte must contain the same ions with which it has to be electroplated.
Question 37.
The table below shows the electronic arrangements of six atoms, A to F.
With respect to the table select the following:
(i) Two atoms from the same group of the periodic table: [1]
(a) D and E
(b) C and D
(c) E and F
(d) C and E
Answer:
(b) Two atoms from the same group of the periodic table must contain same valence electrons. Hence, C and D both having 6 electrons belong to the same group.
(ii) Two noble gases: [1]
(a) A and B
(b) E and F
(c) B and E
(d) D and E
Answer:
(c) B has configuration 2 that means it is helium and E has configuration 2, 8, 8 which refers to Argon. Helium shows fully filled duplet and argon shows fully filled octet. Thus, both B and E are noble gases.
(iii) The atom which is the most electronegative: [1]
(a) A
(b) B
(c) C
(d) F
Answer:
(c) A, C and D are electronegative. As all the three have tendency to gain electron. But C has the maximum tendency out of the three because of its smallest size.
(iv) The atom which has the highest ionization potential: [1]
(a) A
(b) B
(c) E
(d) F
Answer:
(b) The highest ionization potential is of B (Helium). As it is the most stable, having smallest size, therefore, the energy required to remove electron from its outermost shell is maximum.