CBSE Class 10 Science 2020 Outside Delhi Set 1

Question : 16

Total: 30

Complete and balance the following chemical equations :
(i) NaOH(aq)+Zn (s) →
(ii) CaCO3 (s) +H2O(l)+CO2 (g) →
(iii) HCl(aq)+H2O(l)→
OR
During electrolysis of brine, a gas ' G ' is liberated at anode. When this gas ' G ' is passed through slaked lime, a compound ' C ' is formed, which is used for disinfecting drinking water.
(i) Write formula of ' G ' and ' C '.
(ii) State the chemical equation involved.
(iii) What is common name of compound ' C '?
Give its chemical name.

Solution:

(i) 2‌NaOH+Zn‌

t∘C

───▶

‌Na2‌ZnO2+H2
(ii) Calcium carbonate will react with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate.

CaCO3( s)+CO2(g)+H2O(l)→Ca(HCO3)2(aq)

(iii) HCl+H2O→H3O++Cl−
OR
(i) Chlorine gas is given off at the anode. So, G is Cl2; bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH)2]. Bleaching powder is represented as CaOCl2, so C is CaOCl2.
(ii) Ca(OH)2+Cl2→CaOCl2+H2O
(iii) Compound C is bleaching powder, its chemical name is calcium hypochlorite.

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