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Thermodynamics · Question 11

RE-NEET (UG) 2024MCQEasy📈 Topic in 50% papers+4−1
1

Choose the correct statement for the work done in the expansion and heat absorbed or released when 5 litres of an ideal gas at 10 atmospheric pressure isothermally expands into vacuum until volume is 15 litres :

  1. Both the heat and work done will be greater than zero
  2. Heat absorbed will be less than zero and work done will be positive
  3. Work done will be zero and heat will also be zero
  4. Work done will be greater than zero and heat will remain zero

Answer

(3) Work done will be zero and heat will also be zero

Solution

Expansion into vacuum is free expansion: pext = 0

w = -pext V = 0

For an ideal gas at constant temperature, U = 0.

U = q + w

q = U - w = 0

Work done and heat are both zero.

Answer: (3)

RE-NEET (UG) 2024

Keep practising — Thermodynamics

2

For an endothermic reaction: Choose the correct answer from the options given below:

  1. B and D
  2. C and D
  3. A and B
  4. A and C
RE-NEET (UG) 2024
3

For the following reaction at 300 K A2(g) + 3B2(g) 2AB3(g) the enthalpy change is +15 kJ, then the internal energy change is :

  1. 19988.4 J
  2. 200 J
  3. 1999 J
  4. 1.9988 kJ
RE-NEET (UG) 2024
4

Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

  1. H = U + ng RT
  2. H - U = - n RT
  3. H + U = n R
  4. H = U - ng RT
NEET (UG) 2023
5

Which of the following p-V curve represents maximum work done?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET (UG) 2022
6

One mole of an ideal gas at 300 K is expanded isothermally from 1 L to 10 L volume. U for this process is : (Use R = 8.314 J K-1 mol-1)

  1. 0 J
  2. 1260 J
  3. 2520 J
  4. 5040 J
NEET (UG) 2022 (Phase 2)
7

Which one among the following is the correct option for right relationship between CP and CV for one mole of ideal gas?

  1. CV = RCP
  2. CP + CV = R
  3. CP - CV = R
  4. CP = RCV
NEET (UG) 2021
8

For irreversible expansion of an ideal gas under isothermal condition, the correct option is :

  1. U 0, Stotal = 0
  2. U = 0, Stotal = 0
  3. U 0, Stotal 0
  4. U = 0, Stotal 0
NEET (UG) 2021
9

For the reaction, 2Cl(g) Cl2(g), the correct option is :

  1. r H > 0 and r S < 0
  2. r H < 0 and r S > 0
  3. r H < 0 and r S < 0
  4. r H > 0 and r S > 0
NEET (UG) 2020
10

The correct option for free expansion of an ideal gas under adiabatic condition is :

  1. q = 0, T < 0 and w > 0
  2. q < 0, T = 0 and w = 0
  3. q > 0, T > 0 and w > 0
  4. q = 0, T = 0 and w = 0
NEET (UG) 2020
11

In which case change in entropy is negative?

  1. Sublimation of solid to gas
  2. 2H(g) H2(g)
  3. Evaporation of water
  4. Expansion of a gas at constant temperature
NEET (UG) 2019

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