The difference between heat of adsorption of ortho and para hydrogen is $......... \ kJ \ mol^{-1}$.

High purity $(>99.95\,\%)$ dihydrogen is obtained by:

Which one of the following would lose weight on exposure to atmosphere?

Hydrogen can be produced by heating

Dihydrogen can be prepared by which of the following reactions?
$(I)$ Reaction of granulated $Zn$ with dil. $HCl$
$(II)$ Reaction of $Zn$ with aq. $NaOH$
$(III)$ By heating calcium hydrogen carbonate

Which of the following statements is not true?