Question

1. Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
a. To prevent rusting, a layer of ........ metal is applied on iron sheets.
b. The conversion of ferrous sulphate to ferric sulphate is ........ reaction.
c. When electric current is passed through acidulated water ........ of water takes place.
d. Addition of an aqueous solution of ZnSO₄ to an aqueous solution of BaCl₂ is an example of ....... reaction

Answer 1

a. To prevent rusting, a layer of    zinc   metal is applied on iron sheets.

Reason ::  In this method, a thin layer of zinc is applied on iron sheets to prevent rusting/corrosion.  First rusting of zinc takes place (more electropositive than iron). this method is known as galvanization

b. The conversion of ferrous sulphate to ferric sulphate is  Oxidation reaction.

Reason ::    Oxidation means losing of electrons.
2FeSO₄→ Fe₂(SO₄)₃   Ionic reaction Fe²⁺ + SO₄^2-→ 2Fe³⁺ + 3SO₄^2-
As we can observe that in ionic reaction that Fe²⁺ changes to Fe³⁺. In this, the positive charge increases by one unit. This means ferrous ion loses one electron. Thus, the above reaction is an oxidation reaction.

 

c. When electric current is passed through acidulated water  electrolysis   of water takes place.

Reason:: On passing electric current through acidulated water , water decomposes into hydrogen and oxygen gases. This decomposition takes place due to the presence of electrical energy. The reaction takes place is called electrolysis.

d. Addition of an aqueous solution of ZnSO₄ to an aqueous solution of BaCl₂ is an example of  double displacement reaction   reaction

Reason::
On addition of ZnSO₄ and BaCl₂, the following reaction takes place:

ZnSO₄ + BaCl₂→ ZnCl₂ + BaSO₄

In the reaction, the exchange of ions are taking place. The reaction in which exchange of ions take place to form precipitate are called double displacement reaction.