A. Nitrate is the reduced element.
B. Phosphorus is the oxidized element.
C. oxidation half reaction: [tex]\frac{1}{4}[/tex] P4 + 4H2O ⇒ H2PO4- + 6H+ + 5e
D. Reduction half reaction: NO3- +4H+ 3e- ⇒ NO + 2H2O
Explanation:
P4 + NO3–→ H2PO4– + NO(A)
nitrate is the reduced element as it has lower its oxidation state.
phosphorus is the oxidised element as it has increase in oxidation number.
B) OXIDATION REACTION:
Phosphorus has undergone oxidation from P0 to P5
[tex]\frac{1}{4}[/tex] P4 + 4H2O ⇒ H2PO4- + 6H+ + 5e-
C) REDUCTION REACTION:
Nitrate ion had undergone reduction from nitrate anion to nitrous oxide.
N+5 to N+2
NO3- +4H+ 3e- ⇒ NO + 2H2O
REDOX REACTION:
now multiplying oxidation reaction with 3 and the reduction reaction with 5
[tex]\frac{3}{4}[/tex]P4 + 5NO3- +2H+ + 2H2O⇒ 5NO+3H3PO4-