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Day 75: JEE Mains Chemistry

5 questions. Try each one first, then open its answer.

  1. Question 1

    Equilibrium. Asked 2 times: 25 Jan 2023*, 7 Apr 2025 (* = numbers or wording changed that year) See all 2 times it was asked

    121
    One litre buffer solution was prepared by adding 0.10 mol each of NH3{NH}_{3} and NH4Cl{NH}_{4}Cl in deionised water. The change in pH on addition of 0.05 mol of HCl to the above solution is ____\_\_\_\_ ×10−2\times 10^{- 2}. (Nearest integer) (Given : pKb{pK}_{b} of NH3=4.745{NH}_{3} = 4.745 and log⁡103=0.477\log_{10}3 = 0.477 ).

  2. Question 2

    Chemical Kinetics. Asked 2 times: 26 Jun 2022*, 3 Apr 2025 (* = numbers or wording changed that year) See all 2 times it was asked

    30
    In a reaction A+B→CA + B \rightarrow C, initial concentrations of AA and BB are related as [A]0=8[B]0\lbrack A\rbrack_{0}= 8\lbrack B\rbrack_{0}. The half lives of AA and BB are 10 min and 40 min . respectively. If they start to disappear at the same time, both following first order kinetics, after how much time will the concentration of both the reactants be same?

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  3. Question 3

    Organic Chemistry - Some Basic Principles and Techniques. Asked 2 times: 2 Apr 2025*, 3 Apr 2025 (* = numbers or wording changed that year) See all 2 times it was asked

    111
    In Dumas' method for estimation of nitrogen 0.4 g of an organic compound gave 60 mL of nitrogen collected at 300 K temperature and 715 mm Hg pressure. The percentage composition of nitrogen in the compound is (Given : Aqueous tension at 300 K=15 mmHg300\text{ }K = 15\text{ }mmHg )

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  4. Question 4

    Amines. Asked 2 times: 31 Jan 2024*, 2 Apr 2025 (* = numbers or wording changed that year) See all 2 times it was asked

    101
    When a concentrated solution of sulphanilic acid and 1-naphthylamine is treated with nitrous acid ( 273 K ) and acidified with acetic acid, the mass (g) of 0.1 mole of product formed is : (Given molar mass in gmol−1H:1,C:12, N:14gmol^{- 1}H:1,C:12,\text{ }N:14, O : 16, S : 32)

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  5. Question 5

    Equilibrium. Asked 2 times: 23 Jan 2025, 29 Jan 2025 See all 2 times it was asked

    29
    At temperature T , compound AB2( g)AB_{2(\text{ }g)} dissociates as AB2( g)⇌AB(g)+12 B2( g)AB_{2(\text{ }g)}\rightleftharpoons AB_{(g)}+\frac{1}{2}{\text{ }B}_{2(\text{ }g)} having degree of dissociation x (small compared to unity). The correct expression for x in terms of KpK_{p} and p is

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