0.3975 g of an oxide of divalent metal on reduction with hydrogen gives 0.090 g of water. The atomic weight of metal is:

a) 63.5
b) 24
c) 55.5
d) 40

1 answer

MO + H2 ==>M + H2O
0.090 x (molar mass MO/molar mass H2O) = 0.3975
Solve for molar mass MO, subtract 18 to arrive at atomic mass M.