Using the ideal gas equation for the `Cl_2` gas;
`PV = nRT`
We know that `n = m/M` where m is mass and M is molar mass.
`PV = m/MRT`
`PM = (m/V)RT`
`m/V = d` (density)
molar mass of `Cl_2 = 71g/(mol)`
`PM = dRT`
`d = (PM)/(RT)`
`d = (1.6xx71)/(0.082xx(273+50))`
`d = 4.289`
So the density of the gas is `4.289g/(ml)`
So the best suited answer is 4.28 which is answer 2)
`Cl_2` act as an ideal gas.