A gas expands from 50 m3 to 58 m3 at a constant pressure of 105 Nm⁻². Calculate the work done by the gas.

Initial volume ($V_1$) = $50 \, \text{m}^3$
Final volume ($V_2$) = $58 \, \text{m}^3$
Constant pressure ($P$) = $10^5 \, \text{Nm}^{-2}$

The change in volume is the final volume minus the initial volume.

For expansion at constant pressure, the work done by the gas is given by the formula:

Substitute the values of pressure and change in volume:

Since $1 \, \text{N} \cdot \text{m} = 1 \, \text{J}$ (Joule),

Comparing this result with the given options, it matches option D.

The work done by the gas is \boxed{\text{8 \times 10^5 J}}.