In the production of hydrogen by the Bosch process,which of the following is used as a catalyst?

Saline hydrides are known to react with water violently producing fire. Can $CO_2$,a well-known fire extinguisher,be used in this case? Explain.

Consider the following statements and identify which of them are correct:
$I.$ Atomic hydrogen is obtained by applying an electric arc to hydrogen gas.
$II.$ Hydrogen gas does not reduce heated aluminum.
$III.$ Finely divided palladium absorbs a large volume of hydrogen gas.
$IV.$ The reaction of $Na$ with $C_2H_5OH$ yields pure nascent hydrogen.

What is heavy water?

Which one of the following is the most abundant element in the universe?

Given below are two statements :
Statement-$I$: Methane and steam passed over a heated $Ni$ catalyst produces hydrogen gas.
Statement-$II$: Sodium nitrite reacts with $NH_4Cl$ to give $H_2O$,$N_2$ and $NaCl$.
In the light of the above statements,choose the most appropriate answer from the options given below :