The number of neutrons in heavy hydrogen is ......... .

Which of the following metals absorbs hydrogen?

The number of hydrogen molecules possible from its isotopes is

When $1:2$ equivalence ratio of the gases $X$ and $Y$ are heated to $573 \ K - 673 \ K$ at $200-300 \ atm$ in the presence of $ZnO-Cr_2O_3$ catalyst,methanol is formed. Here,the gases $X$ and $Y$ are $X$ and $Y$ respectively.

Identify the reactions in which $H_2$ is liberated? $(i)$ $Zn + NaOH_{(aq)} \longrightarrow$ $(ii)$ $HCOOH \xrightarrow[\text{Conc. } H_2SO_4]{373 \ K}$ $(iii)$ $CH_{4(g)} + H_2O_{(g)} \xrightarrow[Ni]{1270 \ K}$ $(iv)$ $Zn + H^+_{(aq)} \longrightarrow$ $(v)$ $C_{(s)} + H_2O_{(g)} \xrightarrow{1270 \ K}$

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