For the reversible elementary reaction A+B C+D,the forward and reverse rate constants are k f and k r. The equilibrium constant is

GATE 2026 ES – Question 16

Environmental Chemistry · Fundamentals of Environmental Chemistry · 1 mark · Multiple choice

For the reversible elementary reaction $A+B\rightleftharpoons C+D$,the forward and reverse rate constants are $k_f$ and $k_r$. The equilibrium constant is

$k_f+k_r$
$k_fk_r$
$k_f/k_r$
$k_r/k_f$

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Correct answer: (C) $k_f/k_r$

Explanation

At equilibrium the forward and reverse rates are equal: $k_f[A][B]=k_r[C][D]$. Rearranging gives $K=[C][D]/([A][B])=k_f/k_r$. This rate-constant relation applies to the elementary reversible reaction stated. Hence **C**.

GATE 2026 ES – Question 16

Explanation

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