Question

what mass of na2so4.7h2o contains exactly 6.02 x 10²² atoms of oxygen?

Answer 1

A = 6.022* 10^23
m= M/(5*10) Where M = molecular weight of na2so4.7h2o

Answer 2

254 gms of Na2SO4.7H2O contains
$11 \times 6.02 \times {10}^{23}$
atoms of O2. So