Y
Why is helium
monoatomic in nature?

Nitrogen stands out because its atoms share a strong triple bond, making it a very stable substance. The noble gases, such as helium and neon, rarely form molecules at all; they are monatomic.

Explanation:

Noble gases are monoatomic because they have complete octet (apart from Helium, which has duet) , hence they are highly stable on their own and do not react with others to form compounds in standard temperature and pressure conditions. ... All the electron shells in the noble gasses are full of electrons.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.