When an ideal gas in a cylinder was compreswsed isothermally by a piston, the work done on the gas found to be `1.5xx10^(4)` cal. During this process about

Answer

To solve the problem, we need to analyze the isothermal compression of an ideal gas and understand the relationship between work done, heat transfer, and internal energy.

### Step-by-Step Solution:

1. **Understanding Isothermal Process**:
In an isothermal process, the temperature of the gas remains constant. For an ideal gas, this means that the internal energy (U) does not change, i.e., \( \Delta U = 0 \).

2. **Work Done on the Gas**:
The work done on the gas during isothermal compression is given as \( W = 1.5 \times 10^4 \) joules.

3. **First Law of Thermodynamics**:
According to the first law of thermodynamics:
\[ \Delta Q = \Delta U + W \]
Since \( \Delta U = 0 \) for an isothermal process, we can simplify this to:
\[ \Delta Q = W \]

4. **Substituting the Values**:
We substitute the value of work done into the equation:
\[ \Delta Q = 1.5 \times 10^4 \text{ J} \]

5. **Converting Joules to Calories**:
To convert joules to calories, we use the conversion factor \( 1 \text{ cal} = 4.184 \text{ J} \):
\[ \Delta Q = \frac{1.5 \times 10^4 \text{ J}}{4.184 \text{ J/cal}} \approx 3580.65 \text{ cal} \]

6. **Considering Heat Flow Direction**:
Since the work is done on the gas, the gas loses heat to the surroundings. Therefore, the heat transfer \( \Delta Q \) will be negative:
\[ \Delta Q \approx -3580.65 \text{ cal} \]

7. **Final Result**:
Thus, the amount of heat that flowed out of the gas during the isothermal compression is approximately \( -3.58 \times 10^3 \) cal.

### Conclusion:
The correct option, based on the calculations, is that approximately \( 3.6 \times 10^3 \) calories of heat flowed out from the gas.