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Thermodynamics · Question 4

JEE Advanced 2024 Paper 1NumericalEasy📈 Topic in 17% papers+4
1

Consider the following volume−temperature (V−T) diagram for the expansion of 5 moles of an ideal monoatomic gas. [figure] Considering only P-V work is involved, the total change in enthalpy (in Joule) for the transformation of state in the sequence X→Y→Z is . [Use the given data: Molar heat capacity of the gas for the given temperature range, CV,m = 12 J K-1 mol-1 and gas constant, R = 8.3 J K-1 mol-1]

Answer

8120

Solution

For an ideal gas H depends only on T: H = nCp,m T, with Cp,m = CV,m + R = 12 + 8.3 = 20.3 J K-1 mol-1.

X → Y: T stays 335 K (isothermal) ⇒ H1 = 0.

Y → Z: T rises from 335 K to 415 K, T = 80 K.

H2 = 5 20.3 80 = 8120 J

Htotal = 0 + 8120 = 8120 J

Answer: 8120

JEE Advanced 2024 Paper 1

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2

An ideal gas (0.5 mol), initially at 2 bar pressure, is compressed at a constant temperature of 600 K in two steps: first, against a constant external pressure of P bar (2 < P < 8), and then against constant external pressure of 8 bar. At each step, the compression is stopped only when the pressure of the gas becomes equal to the external pressure. The total work done on the gas in these steps is W. Considering all possible values of P (2 < P < 8) and taking the gas constant as R (in J K-1 mol-1), the minimum value of |W| (in J) is

  1. 207R
  2. 600R
  3. 630R
  4. 900R
JEE Advanced 2026 Paper 1
3

List-I contains various physical/chemical processes, and List-II contains combinations of changes in enthalpy ( H) and entropy ( S). Match each entry in List-I to the appropriate entry in List-II, and choose the correct option.

  1. P → 2; Q → 3; R → 5; S → 4
  2. P → 4; Q → 3; R → 5; S → 1
  3. P → 2; Q → 5; R → 1; S → 4
  4. P → 2; Q → 5; R → 1; S → 3
JEE Advanced 2026 Paper 1
4

Considering ideal gas behavior, the expansion work done (in kJ) when 144 g of water is electrolyzed completely under constant pressure at 300 K is . Use: Universal gas constant (R) = 8.3 J K-1 mol-1 ; Atomic mass (in amu): H = 1, O = 16

JEE Advanced 2025 Paper 1

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