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Q.
A gas cannot be liquefied above:
Delhi UMET/DPMTDelhi UMET/DPMT 2006
Solution:
Solution The temperature of a gas above which it cannot be liquified whatever high pressure is applied, is known as its critical temperature.
$T_{c}=\frac{8 a}{27 R b} T_{c}$
for $CO _{2} \rightarrow 31.1^{\circ} C T_{c}$
for $H_{2} \rightarrow-240^{\circ} C T_{c}$
for $O_{2} \rightarrow-118^{\circ} C$
Helium has the least $T_c$