JEE Main 2026 — Jan 22, Shift 1 — Chemistry solution

JEE Main2026Jan 22, Shift 1Chemistry

$A \to$ products (First order reaction).

Three sets of experiment were performed for a reaction under similar experimental conditions.

Run 1 $\Rightarrow$ 100 mL of 10 M solution of reactant A

Run 2 $\Rightarrow$ 200 mL of 10 M solution of reactant A

Run 3 $\Rightarrow$ 100 mL of 10 M solution of reactant A + 100 mL of $H_{2} O$ added.

The correct variation of rate of reaction is

Solution

Rate of a first-order reaction depends only on concentration of A: $rate = k [A]$ . Volume of the solution is irrelevant.

Run 1: $[A] = 10$ M → rate $= 10 k$ .

Run 2: $[A] = 10$ M (same concentration, just more solution) → rate $= 10 k$ .

Run 3: 100 mL of 10 M diluted with 100 mL water → $[A] = 5$ M → rate $= 5 k$ .

So Run 3 $<$ Run 1 $=$ Run 2.

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