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Thermodynamics · Question 28

JEE Main 2025 (Online) 4th April Evening ShiftMCQEasy📈 Topic in 16% papers+4−1
1

Consider the given data : (a) HCl(g) + 10H2O(l) HCl 10H2O; H = -69.01 kJ mol-1 (b) HCl(g) + 40H2O(l) HCl 40H2O; H = -72.79 kJ mol-1 Choose the correct statement :

  1. The heat of dilution for the HCl (HCl 10H2O to HCl 40H2O) is 3.78 kJ mol-1.
  2. Dissolution of gas in water is an endothermic process.
  3. The heat of solution depends on the amount of solvent.
  4. The heat of formation of HCl solution is represented by both (a) and (b).

Answer

(3) The heat of solution depends on the amount of solvent.

Solution

(1) (b) – (a): HCl 10H2O + 30H2O HCl 40H2O

Hdil = -72.79 - (-69.01) = -3.78 kJ mol-1

Heat of dilution is -3.78 kJ mol-1 (heat is released), not +3.78 kJ mol-1. Incorrect.

(2) Both ΔH values are negative dissolution of HCl gas in water is exothermic. Incorrect.

(3) ΔH changes from -69.01 to -72.79 kJ mol-1 when the amount of water changes from 10 to 40 mol heat of solution depends on the amount of solvent. Correct.

(4) Heat of formation refers to formation from elements ( 12H2 + 12Cl2), not from HCl(g); (a) and (b) are enthalpies of solution. Incorrect.

Answer: (3)

JEE Main 2025 (Online) 4th April Evening Shift

Keep practising — Thermodynamics

2

Which of the following properties will change when system containing solution 1 will become solution 2 ? [figure]

  1. Molar heat capacity
  2. Concentration
  3. Gibbs free energy
  4. Density
JEE Main 2025 (Online) 3rd April Morning Shift
3

Given : sub H [C (graphite)] = 710 kJ mol-1 C-H H = 414 kJ mol-1 H-H H = 436 kJ mol-1 C=C H = 611 kJ mol-1 The f H for CH2=CH2 is kJ mol-1 (nearest integer value)

JEE Main 2025 (Online) 3rd April Morning Shift
4

Given below are two statements: In the light of the above statements, choose the correct answer from the options given below

  1. Both Statement I and Statement II are false
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Statement I is false but Statement II is true
JEE Main 2025 (Online) 3rd April Evening Shift
5

A perfect gas (0.1 mol) having Cv = 1.50 R (independent of temperature) undergoes the following transformation from point 1 to point 4. If each step is reversible, the total work done (w) while going from point 1 to point 4 is (-) J (nearest integer) [Given: R = 0.082 L atm K-1 mol-1] [figure]

JEE Main 2025 (Online) 3rd April Evening Shift
6

A sample of n-octane (1.14 g) was completely burnt in excess of oxygen in a bomb calorimeter, whose heat capacity is 5 kJ K-1. As a result of combustion reaction, the temperature of the calorimeter is increased by 5 K. The magnitude of the heat of combustion of octane at constant volume is kJ mol-1 (nearest integer).

JEE Main 2025 (Online) 3rd April Evening Shift
7

[figure] Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?

  1. dq 0
  2. The pressure in the vessel B before opening the stopcock is zero
  3. dw 0
  4. dU 0
JEE Main 2025 (Online) 2nd April Morning Shift
8

Arrange the following in order of magnitude of work done by the system/on the system at constant temperature. (a) | wreversible| for expansion in infinite stages. (b) | wirreversible| for expansion in single stage. (c) | wreversible| for compression in infinite stages. (d) | wirreversible| for compression in single stage. Choose the correct answer from the options given below:

  1. d > c = a > b
  2. c = a > d > b
  3. a > c > b > d
  4. a > b > c > d
JEE Main 2025 (Online) 2nd April Evening Shift
9

Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 2nd April Evening Shift
10

500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given: R = 8.3 J K-1 mol-1

  1. 368 K and 500 J
  2. 348 K and 300 J
  3. 378 K and 300 J
  4. 378 K and 500 J
JEE Main 2025 (Online) 29th January Morning Shift
11

The formation enthalpies, Hf for H(g) and O(g) are 220.0 and 250.0 kJ mol-1, respectively, at 298.15 K, and Hf for H2O(g) is -242.0 kJ mol-1 at the same temperature. The average bond enthalpy of the O-H bond in water at 298.15 K is kJ mol-1 (nearest integer).

JEE Main 2025 (Online) 28th January Morning Shift

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