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Some Basic Concepts of Chemistry · Question 31

JEE Main 2025 (Online) 2nd April Evening ShiftMCQMedium📈 Topic in 19% papers+4−1
1

'x' g of NaCl is added to water in a beaker with a lid. The temperature of the system is raised from 1 C to 25 C. Which out of the following plots, is best suited for the change in the molarity (M) of the solution with respect to temperature? [Consider the solubility of NaCl remains unchanged over the temperature range]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(4) [figure]

Solution

M = nNaClVsolution; the amount of NaCl (x g) is fixed (closed beaker), so M depends only on the volume.

Water has its maximum density (minimum volume) at about 4 C:

1 C 4 C: volume decreases M increases.

4 C 25 C: volume increases (thermal expansion) M decreases.

M first rises steeply to a maximum near 4 C and then falls, as in plot (4).

Answer: (4)

JEE Main 2025 (Online) 2nd April Evening Shift

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2

Choose the correct statements. Choose the correct answer from the options given below :

  1. (B), (C) and (D) Only
  2. (A), (B) and (C) Only
  3. (C), (D) and (E) Only
  4. (A), (D) and (E) Only
JEE Main 2025 (Online) 29th January Morning Shift
3

The molarity of a 70\% (mass/mass) aqueous solution of a monobasic acid (X) is 10-1 M (Nearest integer) [Given: Density of aqueous solution of (X) is 1.25 g mL-1 Molar mass of the acid is 70 g mol-1]

JEE Main 2025 (Online) 28th January Morning Shift
4

Quantitative analysis of an organic compound (X) shows following % composition. C : 14.5\% Cl : 64.46\% H : 1.8\% Empirical formula mass of the compound (X) is 10-1 (Given molar mass in g mol-1 of C : 12, H : 1, O : 16, Cl : 35.5)

JEE Main 2025 (Online) 28th January Morning Shift
5

Concentrated nitric acid is labelled as 75% by mass. The volume in mL of the solution which contains 30 g of nitric acid is . Given : Density of nitric acid solution is 1.25 g/mL.

  1. 32
  2. 40
  3. 55
  4. 45
JEE Main 2025 (Online) 28th January Evening Shift

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