Which of the following is zero during reversible adiabatic expansion of the gas

Options

A. `Delta T`
B. `Delta S`
C. `Delta E`
D. All have zero value

Answer

To solve the question "Which of the following is zero during reversible adiabatic expansion of the gas?", we can follow these steps:

### Step 1: Understand the Adiabatic Process
In an adiabatic process, there is no heat exchange between the system (the gas) and its surroundings. This means that the heat transfer (Q) is equal to zero.

**Hint:** Remember that in an adiabatic process, the system is thermally insulated from its surroundings.

### Step 2: Analyze the Options
We need to evaluate the possible options given in the question. Typically, the options may include:
1. Change in temperature (ΔT)
2. Change in entropy (ΔS)
3. Change in internal energy (ΔU)

### Step 3: Evaluate Change in Temperature (ΔT)
During a reversible adiabatic expansion, the temperature of the gas does change. Although there is no heat exchange, the gas does work on the surroundings, which results in a decrease in temperature.

**Hint:** Consider how work done by the gas affects its internal energy and temperature.

### Step 4: Evaluate Change in Entropy (ΔS)
The change in entropy is defined as ΔS = Q/T. Since Q = 0 in an adiabatic process, it follows that ΔS = 0. Therefore, the change in entropy during a reversible adiabatic expansion is zero.

**Hint:** Recall the relationship between heat transfer and entropy.

### Step 5: Evaluate Change in Internal Energy (ΔU)
According to the first law of thermodynamics, ΔU = Q + W. Since Q = 0, we have ΔU = W. Thus, the internal energy change is not zero; it is equal to the work done by the gas.

**Hint:** Remember that internal energy is related to both heat and work.

### Conclusion
From the analysis, we find that the change in entropy (ΔS) is zero during the reversible adiabatic expansion of the gas. Therefore, the correct answer is:

**Answer:** The change in entropy (ΔS) is zero during reversible adiabatic expansion of the gas.