Question

For real gases van der Waals equation is written as
$\left(P +\frac{an^{2}}{V^{2}}\right)\left(V -nb\right) = nRT$
where, $'a'$ and $'b'$ are van der Waals constants. Set of the gases is $O_{2}, CO_{2}, H_{2}$ and $He$. The gases given in set in decreasing order of $b$ arranged below. Select the correct order from the following.

• A. $He\, > \,H_{2}\, >\, CO_{2}\, > O_{2}$
• B. $O_{2} \,> He\, >\, H_{2} \,> CO_{2}$
• C. $H_{2}\, >\, He\, >\, O_{2}\, >\, CO_{2}$
• D. $CO_{2} \, >\, O_{2}\, >\, He\, >\, H_{2}$

Answer 1

Answer: (D)

van der Waals gas constant 'b' represents effective size of molecules. Therefore, order should be $CO_{2}\, >\, O_{2}\, >\, He\, >\, H_{2}$