Дано
m(ppa H2SO4) = 900 g
W(H2SO4) =10%
--------------------------
m(Na2SO4)-?
m(H2SO4) = 900 * 10% / 100% = 90 g
H2SO4+Na2O-->Na2SO4+H2O
M(H2SO4) = 98 g/mol
n(H2SO4) = m/M = 98 / 90 = 1.09 mol
n(H2SO4) = n(Na2SO4) = 1.09 mol
M(Na2SO4) = 142 g/mol
m(Na2SO4) = n*M = 1.09 * 142 = 154.78 g
ответ 154.78 г , 1.09 моль