States of Matter - Result Question 19
####19. If a gas expands at constant temperature, it indicates that :
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(a) kinetic energy of molecules decreases
(b) pressure of the gas increases
(c) kinetic energy of molecules remains the same
(d) number of the molecules of gas increases
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Solution:
- (c) At any constant temperature the K.E. of gaseous molecules remains same.
The molar kinetic energy of a gas is proportional to its temperature and the proportionality constant is $\frac{3}{2}$ times the gas constant $R$.
$ E_m=\frac{3}{2} RT $
