Question

III. Choose from the following list, as what matches the descriptions given below.
[0, 0, NH, OH,H,O, NH,CI, HCl, Ca, magnesium oxide, helium]
1. A noble gas having only two electrons in its valence shell.​

Answer 1

$\huge \sf{ \underline{Helium}}$

About Helium :-

It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table.

• Symbol: He

• Atomic mass: 4.002602 u

• Atomic number: 2

• Electron configuration: 1s2

• Boiling point: -268.9 °C