The atomic weights of two elements (A and B) are 20 and 40 respectively. If x % of A contains y atoms, how many atoms are present in 2x g of B?

Explanation

Number of moles of `A = x/20`
Number of atoms of `A = x/20 xx N` (N is the Av. Const)
`therefore y=x/20 xx N , x = (20y)/N`
Further,
number of moles of B`=(2x)/40 xx N`
`=(2N)/40 xx (20 y)/N`
=y