CBSE Class 10 Science Chemistry Chemical Reactions and Equations Assignment

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Chemical Reactions And Equations Class 10 Chemistry Assignment Pdf

Class 10 Chemistry students should refer to the following printable assignment in Pdf for Chemical Reactions And Equations in standard 10. This test paper with questions and answers for Grade 10 Chemistry will be very useful for exams and help you to score good marks

Class 10 Chemistry Assignment for Chemical Reactions And Equations

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 MnO42–, 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

Question : The chemical formula of lead sulphate is 
a. Pb2SO4
b. PbSO4
c. Pb2(SO4)3
d. Pb(SO4)2
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:
P-9
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 : What are double displacement reaction? 
Answer : Reactions in which ions are exchanged between two reactants forming new compounds are called double displacement reactions.
AB + CD → AC + BD
These are the reactions in which two different atoms or groups of atoms are displaced by another atoms/groups of atoms.
Example :
i. BaCl2(aq) + Na2SO4(aq) → BaSO4 (s)¯ + 2NaCl (aq)
ii. AgNO3 (aq) + NaCl (aq) → AgCl(s)¯ + NaNO3 (aq)
Such reactions usually occur in ionic compound and are very fast reactions. 
 
Question : Oil and fat containing food items are flushed with nitrogen. Why? 
Answer : In the presence of oxygen in the air, the fats present in the fatty food are oxidised to compounds which have a bad smell i.e. the food becomes rancid. Flushing with nitrogen cuts off the contact of food with oxygen and protects the food from rancidity.
 
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
P-10
 
Question : Name the method used to balance a chemical equation. 
Answer :  There are two methods of balancing chemical equation:
1. Hit and Trail Method:
(i)The symbols and formulae of the reactant and products are written as a skeletal equation.
(ii) Any elementary gas (O2, H2, N2 etc.) appearing on either side of the skeletal equation, is written in the atomic state.
(iii)The formula containing the maximum number of atoms is selected to begin the process of balancing. If this method is not convenient, then balancing of the atoms begin with atoms, which appear minimum number of times.
(iv)Atoms of elementary gases are balanced at the last.
(v) When the balancing is complete, the equation is converted to the molecular form.
 
2. Partial equation method: When equations contain many reactants and products they cannot be balanced by the hit and trial method. They are then balanced by the partial equation method. In this method the overall reaction is assumed to take place through two or more simpler reactions, which can be represented by partial equations. The steps involved are:
(i)The given chemical equation is split into two or more partial equations. 
(ii)Each partial equation is separately balanced by the hit and trial method.
(iii)These balanced partial equations are multiplied with suitable coefficients in order to exactly cancel out those common substances which do not appear in the overall chemical equations.
(iv)The balanced partial equations so obtained, are added to arrive at the balanced chemical equation.
 
Question : Name the type of reaction :Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen. 
Answer :  Reactions in which atoms or ions move from one compound to other to form new compound are known as Displacement reaction.
Zn + H2SO4 →ZnSO4 + H2
Zinc reacts with sulphuric acid to form zinc sulphate and hydrogen this is displacement reaction.
 
Question : Mention five ways by which rusting can be prevented. 
Answer :  1. By painting metal surface with enamel paints.
2. By applying oils and greases on surfaces.
3. By plastic coating on the surfaces.
4. By galvanization.
5. By forming alloys.
6. By Plating
7. Keep away from moisture.
 
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
P-18
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. 
P-19
 
 

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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