redox

A.
2Na + CH3CH2OH → 2CH3CH2O^-Na^+ + H2
Na is oxidized because its oxidation number (O.N.) increases from 0 (in Na) to +1 (in Na^+).
H is reduced because its O.N. decreases from +1 (in -OH) to 0 (in H2).

B.
SO2 + 2NaOH → Na2SO3 + H2O
SO2 + Na2SO3 + H2O → 2NaHSO3
The reactions are not redox because there is no change in O.N. for any element in the reactions.
O.N. : S = +4, O = -2, Na = +1, H = +1 (on both sides)

C.
Cu(OH)2 → CuO + H2O
The reaction is not redox because there is no change in O.N. for any element in the reaction.
O.N. : Cu = +2, O = -2, H = +1 (on both sides)


D.
ZnO + 2HNO3 → Zn(NO3)2 + H2O
The reaction is not redox because there is no change in O.N. for any element in the reaction.
O.N. Zn = +2, O = -2, H = +1, N = +5 (on both sides)

A. adding sodium to ethanol

2Na + CH3CH2OH --> 2CH3CH2ONa + H2

Na is oxidized and hydrogen reduced.

D. adding zinc oxide to concentrated nitric acid

ZnO + 2HNO3 --> Zn(NO3)2 + H2O

This is a neutralization and no oxidation number for any element involved in the reaction.