Question 1

According to the First Law of Thermodynamics, which equation correctly relates the change in internal energy ($$\Delta U$$), heat added to the system ($$Q$$), and work done by the system ($$W$$)?

Accepted Answer

$$\Delta U = Q - W$$

Question 2

A system absorbs 200 J of heat and does 80 J of work on its surroundings. What is the change in internal energy of the system?

Accepted Answer

$$\Delta U = 120\ \mathrm{J}$$

Question 3

In a cyclic process, a system returns to its initial state. What is true about the change in internal energy ($$\Delta U) $$for the system?

Accepted Answer

$$\Delta U = 0$$

Question 4

If a system is isolated and does no work on its surroundings, what happens to its internal energy?

Accepted Answer

It remains constant.

Question 5

For an ideal gas, which of the following statements is true regarding its internal energy?

Accepted Answer

It depends only on the temperature.

Question 6

During an isothermal expansion of an ideal gas, what is the change in internal energy ($$\Delta U$$)?

Accepted Answer

$$\Delta U = 0$$

Question 7

A gas in a rigid container (constant volume) is heated, and its temperature increases by $$\Delta T. $$What is the relationship between the heat added ($$Q) $$and the change in internal energy ($$\Delta U$$)?

Accepted Answer

$$Q = \Delta U$$

Question 8

For an adiabatic process involving an ideal gas, which of the following is true?

Accepted Answer

$$Q = 0$$

Question 9

The change in internal energy of an ideal gas is given by which equation?

Accepted Answer

$$\Delta U = n C_V \Delta T$$

Question 10

Why is more heat required to raise the temperature of an ideal gas at constant pressure than at constant volume?

Accepted Answer

Because some heat is used to do work as the gas expands.

Question 11

The molar heat capacities at constant pressure ($$C_P) $$and constant volume ($$C_V) $$for an ideal gas are related by which equation?

Accepted Answer

$$C_P = C_V + R$$

Question 12

A system has 150 J of heat added to it and does 100 J of work. What is the final change in internal energy?

Accepted Answer

$$\Delta U = 50\ \mathrm{J}$$

Question 13

If 150 J of heat is removed from a system and the system does 100 J of work on the surroundings, what is the change in internal energy?

Accepted Answer

$$\Delta U = -50\ \mathrm{J}$$

Question 14

In which scenario does the internal energy of a system remain unchanged?

Accepted Answer

The heat added to the system equals the work done by the system.

Question 15

A sample of 2 moles of an ideal gas is heated at constant volume. If $$C_V = 12.5\ \mathrm{J/(mol\cdot K)}$$ and the temperature increases by $$10\ \mathrm{K}$$, what is the change in internal energy?

Accepted Answer

$$\Delta U = 250\ \mathrm{J}$$

Question 16

Which of the following is NOT a correct statement about the First Law of Thermodynamics?

Accepted Answer

It states that heat and work are state functions.

Question 17

During a process, a system does 50 J of work and its internal energy increases by 30 J. How much heat was transferred to the system?

Accepted Answer

$$Q = 80\ \mathrm{J}$$

Question 18

Which of the following best describes an adiabatic process for an ideal gas?

Accepted Answer

No heat is exchanged with the surroundings.

Question 19

If the temperature of an ideal gas does not change during a process, what can be said about its internal energy?

Accepted Answer

It remains constant.

The First Law of Thermodynamics and Internal Energy of Ideal Gases

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