Question

When methane is burnt in oxygen to produce $C{O}_2$ and $H_{2}O$, the oxidation number changes by____________.

• A. $-8$
• B. $0$
• C. $+8$
• D. $+4$

Answer 1

The correct option is C $+8$

$\stackrel{-4}{C}{H}_4+2O_2\to \stackrel{+4}{C}\stackrel{-4}{O_2}+2H_{2}O$.
Oxidation number change $=+4-(-4)=+8$.