Calcium cyanamide on treatment with steam under pressure gives $NH_3$ and

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

Hydrogen acts as a reducing agent and thus resembles

Pick out the correct statement regarding the conversion of ortho and para hydrogen.

$H_2SO_4$ acts as a dehydrating agent in its reaction with:

Heavy water is: