How many liters of oxygen are in 4.2 moles of chlorine

There is no oxygen in 4,2 L of chlorine,

Explanation:

However, we can calculate the volume of 4.2 mol of a gas.

You don't give the volume and temperature, so I shall assume the gas is at STP (0 °C and 1 bar).

This looks like a case where we can use the Ideal Gas Law to calculate the volume.

pV = nRT

Data:

p = 1 bar

n = 4.2 mol

R = 0.083 14 bar.L·K⁻¹mol⁻¹

T = 0 °C = 273.15K

Calculations:

1 × V = 4.2 × 0.083 14 × 273.15

    V = 95 L

The volume of 4.2 mol of a gas at STP is