The correct order of events in consumer's behavior due to a change in the price of a commodity is as follows:

1. A consumer demands 2 units of a commodity priced at ₹20 (B) - This represents the initial demand at the original price.
2. There is a fall in the price of the commodity to ₹10 (C) - A price reduction occurs.
3. The quantity demanded of the commodity will increase to 10 units (A) - With the price drop, demand increases.
4. The price elasticity of demand will be above 1 (D) - The increase in demand suggests elastic demand where the percentage change in quantity demanded is greater than the percentage change in price.

So, the correct order is (2) (B), (C), (A), (D).