CUET · CHEMISTRY · PYQ PAPER 2025

Read the passage carefully and answer the questions
The chemical reactions proceed at different rates which depend on various factors like concentration, temperature, etc. Rate law is an expression which relates the rate of reaction with concentration of various reacting species in the reaction. For a first order reaction, the concentration of the reactant after time \(t\) is related with its initial concentration by the relation, \(C=C_0 e^{-k t}\). The rate constants for different orders have different expressions. For a first order reaction, \(k=\frac{2.303}{t} \log \frac{a}{a-x}\), where \(a\) is the initial concentration and \(x\) is the extent of reaction.
The Rate law relates the rate of a chemical reaction to

A The temperature
B The activation energy
C The reaction mechanism
D The concentration of reactants

Verified Solution

Answer & Solution

Correct Answer

(D) The concentration of reactants

Step-by-step Solution

Detailed explanation

The concentration of reactants

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Answer the question on the basis of passage given below:
Aldehydes are generally more reactive than ketones in nucleophilic addition reactions due to steric and electronic reasons. Sterically, the presence of two relatively large substituents in ketones hinders the approach of nucleophile to carbonyl carbon more than aldehydes having only one such substituent Electronically aldehydes are more reactive than ketones because two alkyl groups reduce the elctrophilicity of the carbonyl more effectively than in former.
Match List I with List II.

\(LISTI\)	\(LISTII\)
A. & \(CH _3 CH _2 CH _2 CHO \longrightarrow CH _3 CH _2 CH _2 COOH\)	I. \(CrO _3- H _2 SO _4\)
B. Cyclohexene → Hexane-1,6-dioic acid	II. \(\frac{ H _3 O ^{+}}{\Delta}\)
C. \(CH _3 CH _2 CH _2 CH _2 OH \rightarrow CH _3 CH _2 CH _2 COOH\)	III. Ammonical \(AgNO _3\)
D. \(CH _3 CONH _2 \rightarrow CH _3 COOH\)	IV. \(KMnO _4- H _2 SO _4 / \Delta\)

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Let X be a random variable. Let E(X) and Var(X) denote the mean and the variance of X respectively.
Match List - I with List - II

List - I	List - II
(A) If \(\operatorname{Var}( X )=\alpha\), then \(\operatorname{Var}(2 X +3)\) is	(I) \(11 \alpha\)
(B) If \(E ( X )=\alpha\), then \(E (2 X )\) is	(II) \(6 \alpha\)
(C) If \(\operatorname{Var}( X )=\alpha\), then \(\operatorname{Var}(3 X -\alpha)+\operatorname{Var}(\sqrt{2} X +\beta)\) is	(III) \(4 \alpha\)
(D) If \(E(X) = 3\) \(\frac{5\alpha}{12}, \text{ then E(12X + } \alpha)\) is	(IV) \(2 \alpha\)

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CUET 2025 Medium

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