CUET · CHEMISTRY · PYQ PAPER 2023

Which of the following ionic species has the greatest proton affinity to form a stable compound?

A \(HS^-\)
B \(NH_2^-\)
C \(F^-\)
D \(I^-\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(NH_2^-\)

Step-by-step Solution

Detailed explanation

\(pK_a(NH_3) \approx 38\) \(pK_a(H_2S) \approx 7\) \(pK_a(HF) \approx 3.2\) \(pK_a(HI) \approx -10\) \(NH_2^-\) has the greatest proton affinity.

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

In the cyanide extraction process of silver the oxidising and reducing agents used are:

CUET 2023 Medium

"Match the reaction order with their examples in List-II.

List-I	List-II
(A) First order reaction	(I) \(\text{C}_{12}\text{H}_{22}\text{O}_{11} + \text{H}_2\text{O} \xrightarrow{\text{H}^+} \text{C}_6\text{H}_{12}\text{O}_6 + \text{C}_6\text{H}_{12}\text{O}_6\)
(B) Zero order reaction	(II) \(\text{N}_2\text{O}_5 \rightarrow 2\text{NO}_2 + \frac{1}{2}\text{O}_2\)
(C) Pseudo first order reaction	(III) \(\text{CH}_3\text{COOC}_2\text{H}_5 + \text{NaOH} \rightarrow \text{CH}_3\text{COONa} + \text{C}_2\text{H}_5\text{OH}\)
(D) Second order reaction	(IV) \(2\text{NH}_3\text{(g)} \xrightarrow{\text{1130 K}\text{ Pt}} \text{N}_2\text{(g)} + 3\text{H}_2\text{(g)}\)

Choose the correct answer from the options given below:"

CUET 2023 Easy

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List-I (Vitamins)	List-II (Diseases)
(A) Vitamin K	(I) Pernicious anaemia
(B) Vitamin A	(II) Osteomalacia
(C) Vitamin B12	(III) Increase blood clotting time
(D) Vitamin D	(IV) Night blindness

List - I	List - II
(A) Diamagnetic solid	(I) \(CrO _2\)
(B) Ferromagnetic solid	(II) \(Fe _3 O _4\)
(C) Antiferromagnetic	(III) NaCl
(D) Ferrimagnetic solid	(IV) MnO

List - I	List - II
(A) \(M_{23}\)	(I) -17
(B) \(A_{32}+a_{13}\)	(II) -1
(C) \(A\) (Determinant value)	(III) 0
(D) \(a_{13} A_{12}+a_{23} A_{22}+a_{33} A_{32}\)	(IV) 12