Question

Why is He (helium) gas inert

Answer 1

The atomic weight of helium is 4.003.Helium, like the other noble gases, is chemically inert. Its single electron shell is filled, making possible reactions with other elements extremely difficult and the resulting compounds quite unstable.

Answer 2

Because (He) helium has no free electron . It's atomic no. is 2 which fills the first shell . It doesn't react easily with other .