Solution:
Oxidation number of \(\mathrm{C}\) in \(\mathrm{CH}_{4}\) is \(-4\)
as \(x+4=0 x=-4(x\) is oxidation state of carbon)
oxidation of \(C\) in \(C C l_{4}\) is \(+4\)
as \(x-4=0 x=+4\)
\(\therefore\) Change in oxidation state of carbon is from \(-4\) to \(+4\)