Question

Which of these reactions are redox reactions and why?
1: 6NO + 4NH^3 ---> 5N^2 + 6H^2O
2: 2SO^2 + O^2 ---> 2SO^3
3: SO^3 + H^2O ---> H^2SO^4

Answer 1

it will be number 1.
NO loses oxygen ie its being reduced to N2
NH3 gains oxygen atom ie its being oxidised to H2O