Which is an example of a molecular hydride?

If a mole of $H_2$ molecules is heated to a high temperature,which of the following reactions takes place?

Hydrogen can be prepared by mixing steam and water gas at $500 \, ^oC$ in the presence of $Fe_3O_4$ and $Cr_2O_3$ as catalysts. This process is called:

The sum of the number of neutrons and protons in the radioisotope of hydrogen is

Which element accepts one electron to achieve a noble gas-like configuration?

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