$LPG$ stands for Liquefied Petroleum Gas,which is primarily composed of propane and butane. What is the nature of $LPG$?

One of the chief causative factors of desertification is

What has the Ministry of Environment and Forests initiated to save the major rivers of our country from pollution?

Among the $X$ most polluted cities in the world,Delhi ranked at $Y$ position. Identify $X$ and $Y$.

$A$: $El$ $Nino$ is a climatic change which causes deleterious environmental changes.
$R$: Increased tropospheric ozone due to $El$ $Nino$ causes a shift of climatic regions.

Contribution of individuals: Women of Garhwal/Himachal.