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

Identify the correct statements from the following:
$(i)$ $DDT$ is non-biodegradable.
$(ii)$ Heavy metals are responsible for biomagnification.
$(iii)$ High concentration of $DDT$ disturbs calcium metabolism in birds.
$(iv)$ The concentration of $DDT$ in large fish can be up to $2 \, ppm$.

Which one among the following is likely to have the highest levels of $DDT$ deposition in its body?

What is the effect of $Pb$ (lead) on catalysts?

Which one of the following pairs is not correctly matched?

$5^{\text{th}}$ $June$ is celebrated as: