What is the structural formula of lithium tetrahydridoaluminate?

In which of the following reactions is dihydrogen not evolved?

Given below are two statements:
Assertion $(A)$: Protium and deuterium differ in their rates of reactions.
Reason $(R)$: They have different enthalpies of bond dissociation.
The correct answer is:

Which element does not contain any neutrons?

Water gas is

What is believed to be the second most common element in the universe?