Question

If two molecules of A and B have mass 100 kg and 64 kg and rate of diffusion of A is 12 × 10^-3 then what will be rate of diffusion of B?

Options

• 15 × 10^-3 

• 64 × 10^-3

• 5 × 10^-3 

• 46 × 10^-3

Answer 1

15 × 10^-3 

Explanation:

According to Graham's law, `"r"_"A"/"r"_"B" = sqrt("M"_"B"/"M"_"A")`

Here, `"M"_"A" = (100/2)` kg/molecule,

`"M"_"B" = (64/2)` kg/molecule

r_A = 12 × 10-3 and r_B = ?

`(12 xx 10^-3)/"r"_"B" = sqrt((64//2)/(100//2)) = sqrt(64/100) = 8/10`

`=> "r"_"B" = (12 xx 10^-3 xx 10)/8 = 15xx 10^-3`