AP EAMCET Engineering 26 Apr 2017 Shift 1 Paper

The formal charge is calculated by using the formula shown below.
FC= Number of Valence electrons - [number‌of‌lone‌pair+

1

2

‌number‌of‌bond‌pair]
For first oxygen, formal charge is equal to 6−[6+1]=−1
For second oxygen, formal charge is equal to 6−[4+2]=0
For third oxygen, formal charge is equal to 6−[2+3]=1