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

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

Give the chemical reaction for the preparation of producer gas.

Identify the correct statements from the following.
$(i)$ The number of hydrogen bonded water molecules in copper sulphate pentahydrate is one.
$(ii)$ Lanthanum and zirconium form non-stoichiometric hydrides.
$(iii)$ In solid form of $H_2O$, each oxygen is surrounded by six oxygen in octahedral positions at a distance of $276 \ pm$.

In the reaction:
$2x + B_2H_6 \longrightarrow [BH_2(x)_2]^+ [BH_4]^-$
the amine $x$ will not be:

Carbongene has $X\%$ of $CO_2$ and is used as an antidote for poisoning of $Y.$ Then,$X$ and $Y$ are