In which of the following reactions does hydrogen act as an oxidizing agent?

Which of the following ions are present in the anhydrous mixture of $KF$ and $HF$?

Hydrogen can be obtained from water by

State True or False for the following statements:
$1$. Metals of group $7$,$8$ and $9$ form non-stoichiometric hydrides.
$2$. Pure dihydrogen is obtained by heating hydrocarbons with $H_2O$ vapour in the presence of a $Ni$ catalyst at $1270 \ K$.
$3$. The ionization enthalpy of hydrogen is higher than that of alkali metals.
$4$. Some chemical properties of hydrogen resemble both metals and non-metals.

Calorific value of producer gas is low because of

State the abundance and symbol of protium and deuterium in hydrogen atoms.