CUET · CHEMISTRY · PYQ PAPER 2025

Which of the following does not involve Pt as catalyst?
(A) contact process for making \(H _2 SO _4\).
(B) Ziegler-Nata catalyst.
(C) Adams catalyst, used for reduction.
(D) catalyst to decompose \(KClO _3\) to give \(O _2\).
Choose the correct answer from the options given below:

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

Verified Solution

Answer & Solution

Correct Answer

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

Step-by-step Solution

Detailed explanation

(A) Contact process for making \(H _2 SO _4\): Modern industrial process uses \(V_2O_5\). Does not involve Pt. (B) Ziegler-Natta catalyst: Based on titanium and aluminum compounds. Does not involve Pt. (C) Adams catalyst: Is platinum dioxide \((PtO _2)\). Involves Pt. (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

Match List-l with List-II

List-l (Complex)	List-II (Property)
(A) Fuel Cell	(I) Anode: \(Zn (s) \rightarrow Zn ^{2+}+2 e^{-}\) Cathode: \(MnO _2+ NH _4^{+}+e^{-} \rightarrow MnO ( OH )+ NH _3\)
(B) A secondary cell	(II) Cathode: \(O _2(g)+2 H _2 O (l)+4 e^{-} \rightarrow 4 OH ^{-}(a q)\) Anode: \(2 H _2(g)+4 OH ^{-}(a q) \rightarrow 4 H _2 O (l)+4 e^{-}\)
(C) Mercury cells	(III) \(Pb (s)+ PbO _2(s)+2 H _2 SO _4(a q) \rightarrow 2 PbSO _4(s)+2 H _2 O (l)\)
(D) Leclanche cell (Simplified)	\((I V) Zn ( Hg )+ HgO (s) \rightarrow ZnO (s)+ Hg (l)\)

Choose the correct answer from the options given below :

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Which of the following compound shows optical isomerism ?

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List-l	List-II
(A) Coupling reaction	(I) Primary amines
(B) Hofmann's degradation	(II) Aromatic amines
(C) Isocyanide test	(III) Phenols and aromatic amines
(D) Diazonium salts	(IV) Amide to amine

Which of the following does not involve Pt as catalyst?(A) contact process for making \(H _2 SO _4\).(B) Ziegler-Nata catalyst.(C) Adams catalyst, used for reduction.(D) catalyst to decompose \(KClO _3\) to give \(O _2\).Choose the correct answer from the options given below:

Step-by-step Solution

Which of the following does not involve Pt as catalyst?
(A) contact process for making \(H _2 SO _4\).
(B) Ziegler-Nata catalyst.
(C) Adams catalyst, used for reduction.
(D) catalyst to decompose \(KClO _3\) to give \(O _2\).
Choose the correct answer from the options given below: