Question

the vapour density of certain gas X is 4 times that of Y .the molecular mass of X is M.then molecular mass of Y is
a)4M
b) 0.5M
c) 0.25M
d) 0.33M

Answer 1

hope it helpe to you

Answer 2

The relation between molecular mass and vapour density is given as follows:

Molecular mass= 2× Vapour density

Here, we are considering Vapour density as VD.

As given,

VD of X = 4× VD of Y

So, according to the formula:

In case of X,

M= 2× VD of X

so, M= 2× 4× VD of Y

so, VD of Y= M/8

Now, in case of Y,

Y mol mass= 2× VD of Y

Now placing the value of VD of Y from the previous equation.

= 2 × M/8 = M/4 = 0.25M

So the correct answer is option (C) - 0.25M.

Molecular mass of Y is 0.25M.