Sn(NO3)2-Sn(OH)2-SnO-SnSO4-Sn(OH)2-Na2[Sn(OH)4]-Sn(NO3)2

Sn(NO3)2 + 2NaOH = Sn(OH)2↓ + 2NaNO3
Sn(OH)2 =t°⇒ SnO + H2O
SnO + H2SO4 = SnSO4 + H2O
SnSO4 + 2NaOH = Sn(OH)2↓ + Na2SO4
Sn(OH)2 + 2NaOH = Na2[Sn(OH)4]
Na2[Sn(OH)4] + 4HNO3 = 2NaNO3 + Sn(NO3)2 + 4H2O