1)
SO2: 1(S) + 2(O) = 32.06 + 216.00 = 64.06 g/mol
N2O5: 2(N) + 5(O) = 214.01 + 516.00 = 108.02 g/mol
H2SiO3: 1(Si) + 3(O) + 2(H) = 28.09 + 316.00 + 21.01 = 78.11 g/mol
Na2SO3: 2(Na) + 1(S) + 3(O) = 222.99 + 32.06 + 316.00 = 126.05 g/mol
Al(OH)3: 1(Al) + 3(O) + 3(H) = 26.98 + 316.00 + 3*1.01 = 78.03 g/mol

2)
NO2: 1(N) + 2(O) = 14.01 + 216.00 = 46.01 g/mol
P2O5: 2(P) + 5(O) = 230.97 + 516.00 = 141.94 g/mol
H2CO3: 1(C) + 1(O) + 3(O) + 2(H) = 12.01 + 16.00 + 316.00 + 21.01 = 62.03 g/mol
K2SO4: 2(K) + 1(S) + 4(O) = 239.10 + 32.06 + 416.00 = 174.26 g/mol
Cr(OH)3: 1(Cr) + 1(3) + 3(O) + 3(H) = 52.00 + 316.00 + 3*1.01 = 100.03 g/mol