One mole of hydrogen ($a=0.244{\mathrm{L}}^2\mathrm{atm}\mathrm{mo}{\mathrm{l}}^{-2}$, $b=0.0266\mathrm{L}\mathrm{mo}{\mathrm{l}}^{-1}$) is compressed to $0.100\mathrm{L}$ at $600\mathrm{K}$. The difference $P_{\text{vdW}}-P_{\text{ideal}}$ in atm (nearest integer), with $R=0.0821\mathrm{L}\mathrm{atm}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$, is

Numerical answer type, answer in atm, tolerance 2.