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Chemistry · PYQ NEET UG 2017
हिन्दीMechanism of a hypothetical reaction \( \text{X}_2 + \text{Y}_2 \longrightarrow 2\text{XY} \) is given below:\n(i) \( \text{X}_2 \longrightarrow \text{X} + \text{X} \dots \) fast\n(ii) \( \text{X} + \text{Y}_2 \longrightarrow \text{XY} + \text{Y} \dots \) slow\n(iii) \( \text{X} + \text{Y} \longrightarrow \text{XY} \dots \) fast\nThe overall order of the reaction will be _______.
Correct answer · Option 3
1.5
Explanation
Rate determining step is step (ii): Rate = \( k[\text{X}][\text{Y}_2] \). From step (i) equilibrium, \( K_{\text{eq}} = \frac{[\text{X}]^2}{[\text{X}_2]} \Rightarrow [\text{X}] = K_{\text{eq}}^{1/2}[\text{X}_2]^{1/2} \). Substituting, Rate = \( k'[\text{X}_2]^{1/2}[\text{Y}_2] \). Order = \( 0.5 + 1 = 1.5 \).
