If you do not even understand what chemical warfare is then its a waste talking to you.
Consider the cost of deaths in India due to the following pakistan action,
1. Inflation due to flooding of fake currency
2. Shelling and bombing in the border
3. Killing of BSF soldiers
4. Killings due to terrorists
5. Killings due to bomb blasts
6. Killings due to the drug trade from pakistan....etc..
Yeah, you are too much of a coward to do anything about the deaths of Indians. Spare me your nonsense.
There is NO better way to make pakistan pay. If there was, we would already have done it.
If they are doing all these things then set up a fertiliser factory on banks of Indus.
Now if you call that chemical warfare then i have nothing left to say.