Oxidation of succinate ion produces ethylene and carbon dioxide...

Ethene, ${CO}_{2}, {H}_{2}$ are gases.

So total moles of gas $= 1 + 2 + 1 = 4$

By $2$ Farady$= 4$ mole of gas produced

So, by $0 . 2$ Farady $= 0 . 4$ mole gas produced

$ν = \dfrac{nRT}{P} = \dfrac{0.4 \times 0.0821 \times 273}{1} = 8.96L$