Which set of elements forms stable,covalent,and hydrogen-bonded hydrides?

The most dangerous method of preparing hydrogen would be by the action of $HCl$ and

Identify the catalyst used in the following reaction at $500^{\circ} C$:
$CO + H_2O \rightleftharpoons CO_2 + H_2$

Which will not cause any atmospheric pollution?

Given below are two statements:
Statement $I$ : Nickel is being used as the catalyst for producing syn gas and edible fats.
Statement $II$ : Silicon forms both electron rich and electron deficient hydrides.
In the light of the above statements,choose the most appropriate answer from the options given below:

Complete the following reactions:
$(i)$ $H_{2(g)} + M_mO_{o(s)} \xrightarrow{\Delta} M_{(s)} + H_2O_{(l)}$
$(ii)$ $CO_{(g)} + 2H_{2(g)} \xrightarrow{\Delta, \text{ catalyst}} CH_3OH_{(l)}$
$(iii)$ $C_3H_{8(g)} + 3H_2O_{(g)} \xrightarrow{\Delta, \text{ catalyst}} 3CO_{(g)} + 7H_{2(g)}$
$(iv)$ $Zn_{(s)} + 2NaOH_{(aq)} \xrightarrow{\text{heat}} Na_2ZnO_{2(aq)} + H_{2(g)}$