Thermodynamics and Thermochemistry 1 Question 48
51. Statement I The heat absorbed during the isothermal expansion of an ideal gas against vacuum is zero.
Statement II The volume occupied by the molecules of an ideal gas is zero.
$(2000, \mathrm{~S}, 1 \mathrm{M})$
Passage Based Questions
A fixed mass $m$ of a gas is subjected to transformation of states from $K$ to $L$ to $M$ to $N$ and back to $K$ as shown in the figure. (2013 Adv.)
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Solution:
- Statement I is true.
$$ \begin{array}{rlrl} & & d q & =d E+p_{\text {ext }} d V=0 \ \Delta T & =0 \ \therefore & d E & =0 ; \quad p_{\text {ext }}=0 \ \therefore \quad & p_{\text {ext }} d V & =0 \end{array} $$
Statement II is true. According to kinetic theory of gases, volume occupied by molecules of ideal gas is zero.
However, Statement II is not the correct explanation of Statement I.
