Question

When methane is burnt completely, oxidation state of carbon changes from ______.

Options

• + 2 to - 2

• - 4 to + 4

• 0 to + 4

• + 4 to 0

Answer 1

When methane is burnt completely, oxidation state of carbon changes from - 4 to + 4.

Explanation:

\[\begin{array}{cc}
\ce{CH_{4(g)} + 2O_{2(g)} -> CO_{2(g)} + 2H2O_{(g)}}\\
\phantom{..}\downarrow\phantom{}\downarrow\phantom{.......}\downarrow\phantom{.......}\downarrow\phantom{}\downarrow\phantom{.......}\downarrow\phantom{}\downarrow\phantom{....}\\
\ce{\underline{- 4} + 1}\phantom{........}\ce{0}\phantom{......}\ce{\underline{+ 4} - 2}\phantom{......}\ce{+1-2}\phantom{...}
\end{array}\]

Oxidation state of 'C' atom changes from -4 to +4.