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Some Basic Concepts of Chemistry

JEE Main 2025 (Online) 2nd April Evening ShiftMCQMedium📈 Topic in 18% papers+4−1
Ques. 1JEE Main 2025, 2 April (Evening Shift)

'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)

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Ques. 2JEE Main 2025, 29 January (Morning Shift)

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
Ques. 3JEE Main 2025, 29 January (Evening Shift)

0.1 M solution of KI reacts with excess of H2SO4 and KIO3 solutions. According to equation 5I- + IO3- + 6H+ 3I2 + 3H2O Identify the correct statements : Choose the correct answer from the options given below :

  1. (C) and (D) only
  2. (A) and (B) only
  3. (B) and (C) only
  4. (A) and (D) only
Ques. 4JEE Main 2025, 28 January (Morning Shift)

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]

Ques. 5JEE Main 2025, 28 January (Morning Shift)

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)

Ques. 6JEE Main 2025, 28 January (Evening Shift)

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
Ques. 7JEE Main 2025, 24 January (Morning Shift)

Consider the following reaction occurring in the blast furnace: Fe3O4(s) + 4CO(g) 3Fe(l) + 4CO2(g) 'x' kg of iron is produced when 2.32 103 kg Fe3O4 and 2.8 102 kg CO are brought together in the furnace. The value of 'x' is . (nearest integer) Given: molar mass of Fe3O4 = 232 g mol-1 molar mass of CO = 28 g mol-1 molar mass of Fe = 56 g mol-1

Ques. 8JEE Main 2025, 24 January (Morning Shift)

Xg of benzoic acid on reaction with aq NaHCO3 released CO2 that occupied 11.2 L volume at STP. X is g.

Ques. 9JEE Main 2025, 24 January (Evening Shift)

The elemental composition of a compound is 54.2\% C, 9.2\% H and 36.6\% O. If the molar mass of the compound is 132 g mol-1, the molecular formula of the compound is : [Given : The relative atomic mass of C:H:O=12:1:16]

  1. C4H8O2
  2. C6H12O6
  3. C4H9O3
  4. C6H12O3
Ques. 10JEE Main 2025, 23 January (Morning Shift)

What amount of bromine will be required to convert 2 g of phenol into 2,4,6-tribromophenol? (Given molar mass in g mol-1 of C, H, O, Br are 12, 1, 16, 80 respectively )

  1. 6.0 g
  2. 10.22 g
  3. 20.44 g
  4. 4.0 g
Ques. 11JEE Main 2025, 23 January (Morning Shift)

2.8 10-3 mol of CO2 is left after removing 1021 molecules from its ' x ' mg sample. The mass of CO2 taken initially is Given: NA = 6.02 1023 mol-1

  1. 98.3 mg
  2. 196.2 mg
  3. 150.4 mg
  4. 48.2 mg

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