Question

If an ideal gas compressed during isothermal process then:-

• A. no work is done against gas
• B. heat is rejected by gas
• C. it's internal energy will increase
• D. pressure does not change.

Answer 1

The correct option is B heat is rejected by gas

Given: Compression of ideal gas during isothermal process.

Solution:

It is known that change in internal energy is function of temperature only.

So, $△U=f\left(T\right)$

If temperature is constant then $△U=0$.

Now,$△Q=△U+W$

$\Rightarrow △Q=W$

For isothermal process, $W=\int PdV$

As compression is occuring so $dV<0$

$\therefore W<0$

So, $△Q<0$ (heat is rejected by the system).

Hence, the correct option is B.