Decomposition reactions can be brought about by different forms of energy. Name the three forms of energy that can cause decomposition, and give one example of a reaction for each.
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer
The three forms of energy that cause decomposition reactions are heat, light, and electricity.
- Heat (Thermal decomposition):
$$2\text{Pb(NO}_3)_2(s) \xrightarrow{\Delta} 2\text{PbO}(s) + 4\text{NO}_2(g) + \text{O}_2(g)$$
- Light (Photolytic decomposition):
$$2\text{AgCl}(s) \xrightarrow{\text{sunlight}} 2\text{Ag}(s) + \text{Cl}_2(g)$$
- Electricity (Electrolytic decomposition):
$$2\text{H}_2\text{O}(l) \xrightarrow{\text{electricity}} 2\text{H}_2(g) + \text{O}_2(g)$$
Source: Chapter 1 – Chemical Reactions and Equations, Section 1.2 (Types of Chemical Reactions)
---
Explanation
- The examiner expects all three forms named + one correct equation each — that's 1 mark per pair.
- Use the standard NCERT examples: lead nitrate (heat), silver chloride (light), water (electricity). These are the safest choices.
- Write state symbols and the energy type above the arrow — examiners notice and reward this detail.
- Do not confuse electrolytic decomposition of water with any combustion reaction.