Q.Complete the following reactions:

Dihydrogen is prepared in the laboratory by the action of dilute acids on active metals such as zinc, or by electrolysis of acidified or alkaline water; pure water conducts electricity poorly, so a small quantity of an electrolyte such as dilute $H_2SO_4$ or $NaOH$ is added to furnish free ions and carry the current efficiently, releasing $H_2$ at the cathode and $O_2$ at the anode. Zinc also reacts directly with hot concentrated $NaOH$ solution, liberating $H_2$ and forming sodium zincate: $Zn + 2NaOH \rightarrow Na_2ZnO_2 + H_2$. On the industrial/bulk scale, dihydrogen is obtained mainly from hydrocarbons and coal. Coal gasification passes steam over red-hot coke to give water gas, a mixture of CO and $H_2$: $C(s) + H_2O(g) \xrightarrow{1270\,K} CO(g) + H_2(g)$; its hydrogen yield can be increased by mixing the water …