Calculate the number of (a) `CH_(4)` molecules (b) C-atoms and (c) H-atoms in 25g of `CH_(4)` gas.

Explanation

(a) 25g `CH_(4)=(25)/(16)mol" "CH_(4)`
[`because` molecular mass of `CH_(4)` is 16g]
`therefore`Number of molecules in `(25)/(16)` mol `CH_(4)`
`=6.022xx10^(23)xx(25)/(16)CH_(4)=9.41xx10^(23)`
(b) No. of C-atoms in one `CH_(4)` molecule=1
`therefore`No. of C-atoms in `9.41xx10^(23)CH_(4)` molecules
`=9.41xx10^(23)`
(c) No. of H-atoms in one `CH_(4)` molecules=4
`therefore`No. of H-atoms in `9.41xx10^(23)CH_(4)` molecule
`=4xx9.41xx10^(23)=3.764xx10^(24)`