SnCl2+2NaOH→A+2NaCl
A+2NaOH→B+2H2O
Identify A and B
When hydrated stannous Chloride reacts with alkalis, then White ppt. of stannous hydroxide is formed, which dissolves in excess of alkali to form sodium stannite, Na2SnO2, which further reacts with atmospheric O2 to form Na2SnO4.
SnCl2+2NaOH→Sn(OH)2↓+2NaCl
Sn(OH)2+2NaOH→Na2SnO2+2H2O
Sodium stannite (soluble)