(a) Electricity decomposes into hydrogen and oxygen gas when it passes through acidified water.

2H₂ O → 2H₂ + O₂

(a) Thermal decomposition occurs when heat is applied.

An example of thermal decomposition is the heating of baking soda. The reaction can be written as follows:

2NaHCO₃(s) → CO₂(g) + H₂O(g) + Na₂CO₃(s)