Questions on Metals and Reactions

Questions on Metals and Reactions

Q1. A brown substance ‘X’ on heating in air forms a substance ‘Y’. When hydrogen gas is passed over heated ‘Y’, it again changes back into ‘X’.

i. Name the substances X and Y.

ii. Name the chemical processes occurring during both changes.

iii. Write the chemical equations of the reactions.

Ans:

(i) X : Copper (Cu)   

Y : Copper Oxide (CuO)

(ii) Oxidation of X and Reduction of Y

(iii) 2Cu + O2 → 2CuO

CuO + H2 → Cu + H2O

Q2. Write the commercial name and chemical formula of

a) Sodium Hydroxide

Ans:

Commercial Name: caustic soda

Chemical Name: NaOH

b) Potassium Hydroxide

Ans:

Commercial Name: caustic potash

Chemical Name: KOH

Q3) Give one example each of:

a) thermal decomposition reaction

Ans:

CaCO3 → CaO + CO2 

When heated Calcium Carbonate, decomposes into Calcium Oxide and Carbon Dioxide. 

b) Electrolytic decomposition reaction

Ans:

2H2O→ 2H2 + O2

Dissociation of water

c) Photo decomposition reaction

Ans:

Questions on Metals and Reactions

Decomposition of silver chloride into silver and chloride by light.

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