Formal ch arge $=\left[\begin{array}{l}\text { Totalno. of } \\ \text { valence }^{-} \\ \text {in freestate }\end{array}\right]-\left[\begin{array}{l}\text { Totalno. of } \\ \text { lonepair } \\ \text { electrons }\end{array}\right]-\frac{1}{2}\left[\begin{array}{l}\text { no.of bonding } \\ \text { electons on that } \\ \text { particular atoms }\end{array}\right]$
Formal charge on $\mathrm{C}$-atom $=4-0-\frac{1}{2} \times 8=0$