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:
a. To prevent rusting, a layer of zinc metal is applied on iron sheets.
Explanation:
Galvanization is a method to prevent rusting.
i. In this method, a thin layer of zinc is applied on iron sheets to prevent rusting/corrosion.
ii. First rusting of zinc takes place (more electropositive than iron).
iii. After few seasons, zinc layer goes away.
iv. Then, iron starts rusting.
b. The conversion of ferrous sulphate to ferric sulphate is oxidation reaction.
Explanation:
Oxidation means losing of electrons.
2FeSO4→ Fe2(SO4)3
Ionic reaction Fe2+ + SO42-→ 2Fe3+ + 3SO42-
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.
Explanation:
On passing electric current through acidulated water (a water contains acid), 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.
Electrolysis: 2H2O(l) → 2H2↑ + O2↑
d. Addition of an aqueous solution of ZnSO4 to an aqueous solution of BaCl2 is an example of double displacement reaction.
Explanation:
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.
