Number of chlorine atoms present in DDT are

Which substance is used to extinguish fire in substances like oil, fat and petrol?

Which substance is added in chloroform before the use of it as anaesthetic?

How many $\mathrm{\sigma }$ and $\mathrm{\pi }$ bonds are present in the structure of D.D.T respectively?

In the following sequence of reactions, the gaseous species $\mathrm{A}\text{,} \mathrm{B}\text{,} \mathrm{D}\text{,} \mathrm{E}$, respectively, are