Solutions of Chemical Reactions and Equations (Page No - 45) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 1:
What type of reaction is represented by the digestion of food in our body ?
Solution :
Decomposition reaction.

Question 2:
Name the various types of chemical reactions.
Solution :
The various types of chemical reactions are:

1. Combination reactions.
2. Decomposition reaction.
3. Displacement reaction.
4. Double displacement reaction.
5. Oxidation and reduction reactions.

Question 3:
Why does-the colour of copper sulphate solution change when an iron nail is kept immersed in it ?
Solution :
The colour of copper sulphate solution changes when iron nail is kept immersed in it due to the displacement reaction taking place between iron and copper leading to formation of iron sulphate.

Question 4:
Write the balanced chemical equation for the following reaction :
Zinc + Silver nitrate —–> Zinc nitrate + Silver
Solution :
Zn + 2AgNO₃ —–> Zn(NO₃)₂ + 2Ag

Question 5:
Which term is used to indicate the development of unpleasant smell and taste in fat and oil containing foods due to aerial oxidation (when they are kept exposed for a considerable time) ?
Solution :
Rancidity.

Question 6:
What is the general name of the chemicals which are added to fat and oil containing foods to prevent the development of rancidity
Solution :
Anti-oxidants.

Question 7:
State an important use of decomposition reactions.
Solution :
The digestion of food in the body is an example of decomposition reaction.

Question 8:
What are anti-oxidants ? Why are they added to fat and oil containing foods ?
Solution :
Anti-oxidant is a substance which prevents oxidation. They are added to fat and oil
containing foods so that they do not get oxidized easily and hence do not
turn rancid.

Question 9:
Explain why, food products containing fats and oils (like potato chips) are packaged in nitrogen.
Solution :
Food products containing fats and oils are packaged in nitrogen so that there is no oxygen to cause oxidation of food and make it rancid.

Question 10:
Give one example of a decomposition reaction which is carried out:
(a) with electricity
(b) by applying heat
Solution :
(a) When fused sodium chloride is decomposed by passing electricity, sodium metal is obtained.
(b) When lead nitrate is heated strongly, it breaks down to form lead monoxide, nitrogen dioxide and oxygen.

Question 11:
What type of chemical reaction is used to extract metals from their naturally occurring compounds like oxides or chlorides ?
Solution :
Decomposition
reactions (carried out by electricity).

Question 12:
Name two anti-oxidants which are usually added to fat and oil containing foods to prevent rancidity.
Solution :
BHA (Butylated
Hydroxy Anisole) and BHT (Butylated Hydroxy Toluene).

Question 13:
Write one equation each for the decomposition reactions where energy is supplied in the form of  (a) heat,
(b) light, and (c) electricity.
Solution :

(a) Decomposition reaction where heat is supplied for energy:

 (b) Decomposition reaction where light is supplied for energy:

 (c) Decomposition reaction where electricity is supplied for energy: 

Question 14:
In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the chemical equation of the reaction involved.
Solution :
2AgNO₃ (aq) + Cu (s) —–>Cu(NO₃)₂ (aq) + 2Ag (s)

Question 15:
What type of reactions are represented by the following equations ?

1. CaC03 ——- > CaO + C0₂
2. CaO + H20 ——- > Ca(OH)₂
   
3. 2FeSO₄ ——- >Fe₂0₃ + S0₂ + S0₃
4. NH₄Cl  —–> NH₃+HCl
5. 2Ca+O₂ ——- > 2CaO

Solution :

1. Decomposition.
2. Combination.
3. Decomposition.
4. Decomposition.
5. Combination.