Question

what is the ratio of weight of O2 and He, the mixture of which contains equal number of molecules of equal gas?

Answer 1

Molecular mass of O2 - 32 amu
Molecular mass of he. - 4 amu
(This means that if you take 32 grams of oxygen or 4 grams of Helium it will contain approximately 6.022 X 10 to the power 23 lmolecules of it)

amu ----- atomic mass unit

Let the mass of oxygen taken be Y grams then according to the question the mass of helium is Y grams also. Now to calculate the no of particles we divide the mass taken by amu.

For oxygen we get , Y/32. ------- result 1
For nitrogen we get, Y/4. --------result 2

Now the ratio of no. of particles for oxygen by nitrogen is

Result 1 / Result 2.
which is equals to

Y/32 into Y/4.

By solving we get the ratio

1/8. -------- required ratio