CBSE Class 10 Science Chemistry Chemical Reactions and Equations Assignment

Question. The reaction between aqueous solutions of sodium chloride and silver nitrate is -
a. displacement reaction
b. synthesis reaction
c. double displacement reaction
d. analysis reaction
Answer. C

Question. CH₄ + Cl₂ → CH₃ Cl + HCl reaction is an example of -
a. Synthetic
b. Analytical
c. Displacement
d. Neutralisation
Answer. C

Question. A Brown and bright element “x” when heated in presence of air turns into black substance “y”. If Hydrogen gas is passed over this heating material again “x” is obtained. “x” and “y” are –
a. Cu & CuO
b. S & SO₂
c. C & CO₂
d. Na & NaH
Answer. A

Question. H₂S(g) + Cl₂ (g) →  2 HCl(g) + S(s), The reaction is interpreted as : 
a. H₂S is getting oxidised and Cl₂ is getting reduced
b. H₂S is getting reduced and Cl₂ is getting oxidised
c. Only H₂S is oxidised
d. Both H₂S and Cl₂ are reduced
Answer. A

Question. What is the oxidation number of sulphur in peroxy mono sulphuric acid (H₂SO₅) ?
a. 8
b. 6
c. 5
d. 4
Answer. D

Question. Oxidation is defined as : 
a. loss of electron
b. gain of electron
c. loss of proton
d. gain of proton
Answer. A

Question. From the following metals whose nitrate produces NO₂ gas on heating
a. Na
b. K
c. Pb
d. None of these
Answer. C

Question. The equation given below indicates; NaCl + AgNO₃ → AgCl + NaNO₃ :
a. Chemical decomposition
b. Chemical combination
c. Chemical displacement
d. Chemical double displacement
Answer. D

Question. From the given reactions which is a redox reaction ? 
a. CuO(s) + H₂O(g) → Cu(s) + H₂O(l)
b. 2Cu(s) + O₂(g) → 2CuO(s)
c. C(s) + 2H₂(g) → CH₄(g)
d. 4Al(s) + 3O₂(g) → 2Al₂O₃(s)
Answer. C

Question. Displacement reaction is : 
a. CaO (s) + H₂O(l) → Ca(OH)₂ (aq)
b. Pb(s) + CuCl₂(aq) → PbCl₂(aq) + Cu(s)
c. MnO₂(s) + 4HCl(l) → MnCl₂\(s) + 2H₂O(l) + Cl₂(g)
d. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
Answer. B

Question. Identify the type of reaction for each of the following as 
Combination –(p)
Decomposition –(q)
Displacement –(r)
Double displacement –(s) or combustion – (t)
(i) A compound break apart into its elements
(ii) A metal and a non metal react to form an ionic compound.
(iii) A compound of hydrogen and carbon reacts with oxygen to produce carbon-dioxide and water.
(iv) Silver ion from Ag(NO3) (aq.) forms a precipitate with bromide ion from KBr aq.
a. (i)-(q), (ii)-(p), (iii)-(r), (iv)-(s)
b. (i)-(q), (ii)-(p), (iii)-(t), (iv)-(s)
c. (i)-(s), (ii)-(r), (iii)-(q), (iv)-(p)
d. (i)-(p), (ii)-(t), (iii)-(q), (iv)-(r)
Answer. B

Question. Which of the following is endothermic reaction ?
a. C(s) + O₂(g) → CO₂(g)
b. N₂(g) + O₂(g) → 2NO(g)
c. 2H₂(g) + O₂(g) → 2H₂O(l)
d. 2CH₃OH (l) + 3O₂(g) → 2CO₂(g)+4H₂O(l)
Answer. B

Question. In which of the following reactions H₂O₂ acts as a reducing agent :
a. H₂O₂ + 2H+ + 2e– → 2H₂O
b.  H₂O₂ – 2e– → O₂ + 2H+
c.  H₂O₂ + 2e– → 2OH–
d.  H₂O₂ + 2OH– – 2e– → O₂ + 2H₂O
a. a.,c.
b. b.,d.
c. a.,b.
d. c., d.
Answer. C

Question. Precipitate formation during chemical reaction is indicated by this arrow :
a. ↑
b. →
c. ↓
d. ←
Answer. B

Question. The chemical reaction HNO₃ + KOH → KNO₃ + H₂O is an example of
a. neutralization
b. double displacement
c. neutralization and double displacement
d. combination
Answer. B

Question. In the reaction SO₂ (g) + 2H₂S(g) → 3S + 2H₂O(g) the reducing agent is
a. SO₂
b. H₂O
c. H₂S
d. S
Answer. C

Question. Which of the following is reduction reaction ?
a. Bleaching of coloured objects using moist chlorine
b. Rancidity of fats
c. Thermite process involving the reaction of chromium oxide (or) iron oxide with alumini
d. The poling process involving the removal of impurities from a molten metals
Answer. C

Question. Hydrolysis of water is which type of following reactions? 
a. Endothermic
b. Decomposition
c. Both 1 and 2
d. Combination
Answer. C

Question. When a burning splinter is brought near the gas jar containing hydrogen gas a popping sound is observed. It is due to
a. exothermic
b. endothermic
c. exothermic and endothermic
d. none of these
Answer. A

Question. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be 
a. calcium
b. carbon
c. silicon
d. iron
Answer. A

Question. Identify the correct oxidant and reductant in the following reaction : 
PbS + 4H₂O₂ → PbSO₄ + 4H₂O
a. PbS – Oxidant
H₂O₂ – Reductant
b. PbS – Reductant
PbSO₄ – Oxidant
c. PbS – Reductant
H₂O₂ – Oxidant
d. H₂O₂ – Oxidant
H₂O – Reductant
Answer. C

Question. Sodium carbonate is kept open in the air it looses crystalline water. The process is called:
a. Hygroscopy
b. Deliquescent
c. Efflorescence
d. None of the above
Answer. C

Question. Which out of the following solutions will give a white precipitate when common salt solution is added to it : 
a. KNO₃ solution
b. AgNO₃ solution
c. Ba(NO₃)₂ solution
d. Mg(NO₃)₂ solution
Answer. B

Question. Match the given column-I with column-II and choose the correct option : 
                I                                       II
a. 2Mg + O₂→ 2MgO                  i. Exothermic reaction
b. CaO+H₂O→Ca(OH)₂              ii. Dissociation
c. 2 AgCl → 2Ag +Cl₂                iii. Reduction
d. CuO +H₂ → Cu+H₂O             iv. Oxidation
a. a-i, b-ii, c-iii, d-iv
b. a-ii, b-i, c-iv, d-iii
c. a-iv, b-iii, c-i, d-ii
d. a-iv, b-i, c-ii, d-iii
Answer. D

Question. When KMnO₄ acts as an oxidising agent and ultimately forms MnO₄^2–, MnO₂, Mn₂O₃ and Mn²⁺, then the number of electrons transferred in each case is : 
a. 4, 3, 1, 5
b. 1, 5, 3, 7
c. 1, 3, 4, 5
d. 3, 5, 7, 1
Answer. C

Question. Which of the following is a redox reaction ? 
a. NaCl + KNO₃ → NaNO₃ + KCl
b. CaC₂O₄ + 2 HCl → CaCl₂ + H₂C₂O₄
c. Mg (OH)₂ + 2 NH₄Cl → MgCl₂ + 2 NH₄OH
d. Zn + 2 AgCN → 2 Ag + Zn (CN)₂
Answer. D

Question. The oxidation state of Cr in [Cr(NH₃)₄Cl₂]⁺ is : 
a. + 3
b. + 2
c. + 1
d. 0
Answer. A

Question. Which of the following chemical reactions depicts the oxidizing behaviour of H₂SO₄?
a. 2HI + H₂SO₄ → I₂ + SO₂ + 2H₂O
b. Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
c. NaCl + H₂SO₄ → NaHSO₄ + HCl
d. 2PCl₅ + H₂SO₄ → 2POCl₃ + 2HCl + SO₂Cl₂
Answer. A

Question. In which of the following reactions H₂O₂ acts as a reducing agent ? 
a. H₂O₂ + 2H+ + 2e¯ → 2H₂O
b. H₂O₂ – 2e¯ → O₂ + 2H+
c. H₂O₂ + 2e¯ → 2OH¯
d. H₂O₂ + 2OH¯ – 2e¯ → O₂ + 2H₂O
a. a., b.
b. c., d.
c. a., c.
d. b., d.
Answer. D

Question. In balancing the reaction.
xH₂S + 2NaNO₃ + 2HCl → y S + zNO + kNaCl + 4H₂O
one would get x,y, z and k, respectively, as 
a. 3,3,2 and 2
b. 2,2,3 and 3
c. 3,3,4 and 4
d. 4,4,3 and 3
Answer. A

Answer : B

 

Question :  Heat is evolved during 

a. Combination Reaction

b. Displacement Reaction

c. Endothermic Reaction

d. Combustion Reaction

Answer :  D

Explanation: Burning takes place in combustion so it is an exothermic reaction

 

Question : When zinc metal is dipped in copper sulphate solution 

a. No reaction takes place

b. The solution remains blue and copper metal gets deposited

c. The solution becomes colourless and reddish brown copper metal gets deposited

d. The solution becomes green and copper metal gets deposited

Answer : C

Explanation:

Zinc is more reactive than copper. zinc displace copper from copper sulphate and Copper metal is deposited.

 

Question : Which of the following decolourizes a blue solution of copper sulphate? 

a. Al

b. Zn

c. Fe

1. (A), (B) and (C)

2. (B) only

3. (A) only

4. (C) only

Answer : A

Explanation: All Zn , Al and Fe are above Cu in the reactivity series so they can displace Cu from CuSO₄ Solution.

 

Question :  Choose a displacement reaction. 

a. burning of metals

b. addition of more active metal to a solution of a less active metal compound.

c. extraction of metals.

d. electrolysis

Answer : B

Explanation: Reactions in which atoms or ions move from one compound to other to form new compound are known as Displacement reaction.

A general displacement reaction can be represented using chemical equation as follows:

A + BC → AC + B

Displacement reaction takes place only when ‘A’ is more reactive than B. If ‘B’ is more reactive than ‘A’, then ‘A’ will not displace ‘C’ from ‘BC’ and reaction will not be taken place.

Example: When zinc reacts with hydrochloric acid, it gives hydrogen gas and zinc chloride.

 

 

Question : Why are food items packed in aluminium foils? 

Answer :  A protective coating of aluminium oxide (Al₂O₃) is formed on the surface of the foil which prevents it from getting corroded in the presence of air and water. Hence, food items are saved from getting spoilt when packed in aluminium foils.

 

Question : Write the formula and then balance the following equations. 

a. Butane (C₄H₁₀) + Oxygen Carbon dioxide + Water

b. Magnesium + Silver nitrate Magnesium nitrate + Silver

c. Lime water + Carbon dioxide Calcium carbonate + Water

d. Sodium + Water Sodium hydroxide + Hydrogen

e. Calcium carbonate + Water + Carbon dioxide Calcium bicarbonate 

Answer : The formula and balanced equations are:

a. Butane (C₄H₁₀) + Oxygen → Carbon dioxide + Water

2C₄H₁₀ + 13O₂ + → 8CO₂ + 10H₂O

b. Magnesium + Silver nitrate →Magnesium nitrate + Silver

Mg + 2AgNO₃ → Mg(NO₃)₂ + 2Ag

c. Lime water + Carbon dioxide →Calcium carbonate + Water

Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

d. Sodium + Water →Sodium hydroxide + Hydrogen

2Na + 2H₂O → 2NaOH + H₂

e. Calcium carbonate + Water + Carbon dioxide →Calcium bicarbonate

CaCO₃ + H₂O + CO₂ →Ca(HCO₃)₂

 

Question :Write the formula and then balance the following equation.

Red lead oxide →Lead monoxide + Oxygen

Answer : Red lead oxide Lead monoxide + Oxygen

Question : Translate the following statement into a chemical equation and then balance it :

Barium chloride reacts with aluminium sulphate to give aluminium. 

Answer :  Barium chloride reacts with aluminium sulphate to give aluminium and separates Barium sulfate(BaSO₄).

3BaCl₂(aq) + Al₂(SO₄)₃ (aq) → 2AlCl₃(aq) + 3BaSO₄(s)↓

 

Question : i. Identify the type of reactions taking place in each of the following cases and write the balanced chemical equations for the reactions

a. Barium chloride solution is mixed, with copper sulphate solution and a white precipitate is obtained.

b. On heating copper powder in air, the surface of the copper powder turns black.

ii. What happens when hydrogen gas is passed over the heated copper oxide? Write the chemical equation involved in this reaction. 

Answer : . i. a. BaCl₂ (aq) + CuSO₄ (aq) → BaSO₄ (s) + CuCl₂ (aq)

Double decomposition reaction

Redox reaction, here Cu is changing into CuO. This is oxidised and oxygen is getting reduced by adding metal to it.

ii. If hydrogen gas is passed over heated material (CuO) the black coating on the surface turns brown as the reaction takes place and copper is obtained. 

 

 

1 MARKS QUESTIONS:

1) What is meant by a chemical reaction ?

2) On what basis is a chemical equation balanced? 

3) Write a balanced chemical equation for the reaction between sodium chloride and silver nitrate indicating the physical state of the reactant and the products.

4) What are the various in which a chemical equation can be made more informative.

5) Identify the type of reaction in the following examples. 

a) Na₂SO₄ + BaCl₂→ BaSO₄ + 2NaCl.

b) N₂+ 3H₂→ 2NH₃

c) 2Pb (NO₃)₂ →2PbO +4 NO₂ + O₂

d) Zn + 2 Ag NO₃→Zn (NO₃)₂ + 2Ag

2 MARKS QUESTIONS:

6) Using balanced chemical equation explain the difference between a displacement reaction and double displacement reaction. 

7) Define the following terms with examples.

a) Oxidation

b) Reduction

c) Corrosion

d) Redox Reaction

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