Density of neon will be highest at

From ideal gas equation, $\mathrm{PV}=\mathrm{nRT} = \left(\frac{\mathrm{w}}{\mathrm{m}}\right)\mathrm{RT}$

So, the expression for density, $\mathrm{d}=\left(\frac{\mathrm{PM}}{\mathrm{RT}}\right)$ .

At low temperature and high pressure density is higher

Thus, the density of neon will be highest at 0 ⁰C, 2 atm.