Which of the following expression is correct for the rate of reaction given below:

\(5Br^-(aq) + BrO_3^-(aq) + 6[H^+](aq) \longrightarrow 3Br_2(aq) + 3H_2O(l)\)

\(\frac{\Delta [Br^-]}{\Delta t} = \frac{5}{6}\frac{\Delta [H^+]}{\Delta t}\)

The correct answer is option is 3. \(\frac{\Delta [Br^-]}{\Delta t} = \frac{5}{6}\frac{\Delta [H^+]}{\Delta t}\).

To determine the rate expression for a chemical reaction, you can use the coefficients of the reactants and products in the balanced chemical equation. The rate of reaction is often expressed in terms of the change in concentration of reactants or products over time.
For the given reaction:
\[ 5\text{Br}^-(aq) + \text{BrO}_3^-(aq) + 6\text{H}^+(aq) \longrightarrow 3\text{Br}_2(aq) + 3\text{H}_2O(l) \]
The rate expression is related to the reactants involved, and it can be expressed as:
\[ -\frac{1}{5}\frac{\Delta [\text{Br}^-]}{\Delta t} = -\frac{\Delta [\text{BrO}_3^-]}{\Delta t} = -\frac{1}{6}\frac{\Delta [\text{H}^+]}{\Delta t} =\frac{1}{3}\frac{\Delta[Br_2]}{\Delta t} = \frac{1}{3}\frac{\Delta [H_2O]}{\Delta t}\]
So, the correct expression for the rate of the reaction is:
\[ \frac{1}{5}\frac{\Delta [\text{Br}^-]}{\Delta t} = \frac{1}{6}\frac{\Delta [\text{H}^+]}{\Delta t} \]
Therefore, the correct answer is:(3) \(\frac{\Delta [\text{Br}^-]}{\Delta t} = \frac{5}{6}\frac{\Delta [\text{H}^+]}{\Delta t}\)