As I told at beginning, the oxidation numbers are keys to this problem
SnCl2 +2, -1 => +4, 0(Cl2, even more with other oxidizers)
KI; I -1 => 0 (I2, up to +7)
C2H6O; C -2 (mean value) => up to +4(in CO2)
NaNO2; N +3 => up to +5 (in NO3-)
no ON change in E
Every periodic table contains typical oxidation numbers for all elements.
K, Na, Al, S, H, O - no change in ONs
Note C - ONs for C and H are very close. We always use +1 for H in organic compounds.
If you are familiar with ONs and periodic table the solution needs less than 1 minute.