The relative molecular mass of the gas : 64 g/mol
<h3>Further explanation</h3>
Given
Helium rate = 4x an unknown gas
Required
The relative molecular mass of the gas
Solution
Graham's Law

r₁=4 x r₂
r₁ = Helium rate
r₂ = unknown gas rate
M₁= relative molecular mass of Helium = 4 g/mol
M₂ = relative molecular mass of the gas
Input the value :

The correct option is B.
Stars live out most of their lives at MAIN SEQUENCE. Stars generally are divided into three major stages, these are:
1. Pro stars and pre-main sequence star
2. Main sequence and giant star
3. Variable stars
Major stages in the life of a star can last for millions of years.
It is because sodium is one of the most reactive metals.
There is a reaction would take place between magnesium and sodium chloride.
The chemical reaction between these two metals is given below.
It is Mg + 2NaCl >> MgCl2. + 2Na.
The symbol of this chemical element is Na.
It has the atomic number of eleven
Hope this helps *smiles*