ANS:A - 2M

To solve this problem, let's denote the molecular weight of gas X as 𝑀𝑥Mx​ and the molecular weight of gas Y as 𝑀𝑦My​. Given that the density of gas X is twice that of gas Y, we can express this relationship mathematically using the formula for density: Density=MassVolumeDensity=VolumeMass​ Since density is directly proportional to mass, we can write: Density of X=2×Density of YDensity of X=2×Density of Y Now, density is also inversely proportional to molecular weight when comparing gases at the same temperature and pressure. So, we can write: 𝑀𝑥𝑀𝑦=Density of YDensity of X=12My​Mx​​=Density of XDensity of Y​=21​ Given that the density of Y is directly proportional to its molecular weight, we can conclude that the molecular weight of gas X is half that of gas Y. So, the molecular weight of gas X will be 𝑀𝑦22My​​. Therefore, the correct answer is 𝑀𝑦/2My​/2.