With which of the following does hydrogen combine directly?

Which is the lightest gas?

Which of the following statements about $H_2SO_4$ is incorrect?

Match List-$I$ (Fuels) with List-$II$ (Composition) and select the correct answer using the codes given below the lists.

List-$I$ (Fuels)	List-$II$ (Composition)
$A$. Water gas	$i$. $A$ mixture of $CO$ and $N_2$
$B$. Producer gas	$ii$. Methane
$C$. Coal gas	$iii$. $A$ mixture of $CO$ and $H_2$
$D$. Natural gas	$iv$. $A$ mixture of $CO$,$H_2$,$CH_4$ and $CO_2$

Choose the correct sequence for $A-B-C-D$ respectively:

In $para-hydrogen$,what is the nature of the electron spin?

In the manufacture of hydrogen from water gas $(CO + H_2)$,which of the following is the correct statement?