Question

If the ratio of rates of diffusion of gases X and Y is 1 : 0.7 and molecular weight of Y is 45. The molecular weight of X will be ______.

Options

• 64

• 16

• 22

• 32

Answer 1

If the ratio of rates of diffusion of gases X and Y is 1 : 0.7 and molecular weight of Y is 45. The molecular weight of X will be 22.

Explanation:

Rate of diffusion is inversely proportional to the square root of molecular weight.

i.e.  `"R" prop 1/sqrt"M"`

`"R"_x/"R"_y = sqrt("M"_y/"M"_x)`

`1/0.7 = sqrt(45/"M"_"X")`

Bu squaring both sides,

`1/0.49 = 45/"M"_"X"`

`=> "M"_"X" = 22.05~~ 22`