When steam is passed over red hot iron,the substances formed are

Which one of the following methyl diboranes does not exist?

Formic acid is heated with conc. $H_2SO_4$ at $100^{\circ}C$ to form $A$ and $B$. When $Fe_2O_3$ is heated strongly with $B$,the products formed are $C$ and $D$. $C$ can also be obtained by reacting $CaCO_3$ with dil. $HCl$. What is $D$?

Heavy water is:

Pure dihydrogen $(99.95\%)$ is obtained by the electrolysis of

The method for preparation of water gas is