Consider an aqueous solution 0.1 M each in HOCN, HCOOH, `(COOH)_2` and `H_3PO_4` for HOCN, we can write `K_a(HOCN)=([H^+][OCN^-])/([HOCN]),[H^+]` in the expression refers to:

Options

A. `H^(+)` ions released by `HOCN`
B. Sum of `H^(+)` ions released by all monoprotic acids
C. Sum of `H^(+)` ions released only the first dissociation of all the acids
D. Overall `H^(+)` ion concentration in the solution.

Explanation

To solve the question regarding the expression for \( K_a \) of HOCN and the meaning of \([H^+]\) in the expression, we can follow these steps:

### Step 1: Understand the Dissociation of HOCN
The dissociation of HOCN (cyanous acid) can be represented as:
\[ \text{HOCN} \rightleftharpoons \text{H}^+ + \text{OCN}^- \]
From this dissociation, we can see that HOCN releases \([H^+]\) ions into the solution.
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