CUET · CHEMISTRY · PYQ PAPER 2023

Which of the following statements about gold (Au) element are correct ?
(A) quad Gold occurs in nature in native state.
(B) quad Gold discolves in aqua-regia.
(C) quad Gold is extracted by leaching the metal with dilute NaCN .
(D) \quad Leaching is followed by replacement reaction.
Choose the correct answer from the options given below :

A (B), (C), (D) only
B (A), (C), (D) only
C (A), (B), (C) only
D (A), (B), (C) and (D)

Verified Solution

Answer & Solution

Correct Answer

(D) (A), (B), (C) and (D)

Step-by-step Solution

Detailed explanation

(A), (B), (C) and (D)

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

The limiting molar conductivities for \(\mathrm{H}^{+}, \mathrm{Na}^{+}, \mathrm{Cl}^{-}, \mathrm{CH}_3 \mathrm{COO}^{-}\)are \(349.6,50.1,76.3,40.9 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\), respectively, in water at 298 K.
Match List-l and List-II

List-I	List-II
Electrolyte	\(\Lambda_m^o\)
(A) HCl	(I) \(390.5 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\)
(B) NaCl	(II) \(126.4 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\)
(C) \(\mathrm{CH}_3 \mathrm{COONa}\)	(III) \(425.9 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\)
(D) \(\mathrm{CH}_3 \mathrm{COOH}\)	(IV) \(91.0 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}\)

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The rate of a chemical reaction doubled for every \(10^{\circ} C\) rise in temperature. If the temperature is raised by \(50^{\circ} C\), the rate of reaction will be

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Match List-l with List-II:

List-I (Interspecies Relationships)	List-II (Features)
(A) Commensalism	(I) One species is benefitted at the expense of the other
(B) Mutualism	(II) One species is harmed and the other is unaffected
(C) Amensalism	(III) Both the species are benefitted
(D) Parasitism	(IV) One species benefits and other remains unaffected

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