Which of the following is a Bronsted acid ?
(i) `HCN` , (ii) `H_(2)PO_(4)^(-)`
(iii) `NH_(4)^(+)` , (iv) `HCI`

Options

A. (i), (iii)
B. (i), (ii), (iii), (iv)
C. (ii), (iii)
D. (i), (iii), (iv)

Answer

B

Explanation

A Bronsted acid is any species that can donate a proton `(H^(+))`. It could be neutral or charged.
`HCN rarr H^(+)+CN^(-)`
`H_(2)PO_(4)^(-)rarr H^(+)+HPO_(4)^(2-)`
`NH_(4)^(+)rarr H^(+)NH_(3)`
`HCI rarr H^(+)+CI^(-)`.