Which one of the following ionic species has the greatest proton affinity to form stable compound ?

Options

A. `HS^(-)`
B. `NH_(2)^(-)`
C. `F^(-)`
D. I^(-)`

Answer

3

Explanation

For the oxyacids, the greater the number of highly electronegative oxygen atoms in the molecules, the more the electron density is pulled away form the `H` atom and the weaker the hydrogen -oxygen bond. As a result, an acid with numerous oxygen atoms is more easily ionized and hence stronger. Thus the correct order of acidic strength is