Question

Which of the following is not likely to be one of these four gases?

• A. $He$
• B. $Kr$
• C. $C{H}_4$
• D. An ideal gas

Answer 1

Answer: (A)

$He$

$He$ is not likely to be one of these four gases.
None of the four gases in the graph shows positive deviation from ideal behavior.
The gas $A$ shows zero deviation and the gases $B,C$ and $D$ shows negative deviation from ideal behavior.
$He$ (and hydrogen) shows positive deviation from ideal gas behavior due to very small mass due to which the inter-molecular forces of attraction are extremely small even at low pressures.
The factor $a/V^2$ can be neglected and the van der waals equation reduces to $PV=RT+Pb$