FeS + H₂SO₄ ⟶ FeSO₄ + H₂S is an example of:

1. Displacement reaction
2. Double decomposition reaction
3. Decomposition reaction
4. Combination reaction

Name

(a) a carbonate which does not decompose on heating.

(b) a nitrate which produces oxygen as the only gas.

(c) a compound which produces carbon dioxide on heating

(d) a nitrate which produces brown gas on heating.

Define :

(a) Photochemical reaction

(b) Electrochemical reaction

Give one example in each case.

Give an example of a reaction where the following are involved

(a) Evolution of heat

(b) Absorption of heat

(c) High pressure is required