Which of the following is correct expression for 1st law of thermodynamics under adiabatic condition?

Options

A. `Delta U = Q + W`
B. `Delta U = Q -W`
C. `Q = -W`
D. `Delta U = W`

Answer

To solve the question regarding the correct expression for the first law of thermodynamics under adiabatic conditions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the First Law of Thermodynamics**:
The first law of thermodynamics is expressed as:
\[ \Delta U = Q + W \]
where:
- \(\Delta U\) = change in internal energy
- \(Q\) = heat added to the system
- \(W\) = work done on the system

2. **Identifying Conditions of Adiabatic Process**:
In an adiabatic process, there is no heat exchange with the surroundings. This means that:
\[ Q = 0 \]

3. **Substituting into the First Law**:
Since \(Q = 0\) in an adiabatic process, we can substitute this into the first law equation:
\[ \Delta U = 0 + W \]
which simplifies to:
\[ \Delta U = W \]

4. **Conclusion**:
Therefore, under adiabatic conditions, the correct expression for the first law of thermodynamics is:
\[ \Delta U = W \]

### Final Answer:
The correct expression for the first law of thermodynamics under adiabatic conditions is:
\[ \Delta U = W \]