Hydrogen can be prepared by mixing steam and water gas at $500 \, ^oC$ in the presence of $Fe_3O_4$ and $Cr_2O_3$ as catalysts. This process is called:

Hydrogen is not obtained when zinc reacts with

What is obtained by the reaction of $HCOOH$ with concentrated $H_2SO_4$?

The correct statements among $(a)$ to $(d)$ regarding $H_2$ as a fuel are:
$(a)$ It produces fewer pollutants than petrol.
$(b)$ $A$ cylinder of compressed dihydrogen weighs $\sim 30$ times more than a petrol tank producing the same amount of energy.
$(c)$ Dihydrogen is stored in tanks of metal alloys like $NaNi_5$.
$(d)$ On combustion,the values of energy released per gram of liquid dihydrogen and $LPG$ are $142$ and $50 \ kJ,$ respectively.

Very pure hydrogen $(99.9 \%)$ can be made by which of the following processes?

Hydrogen is