Answer : 2 moles of chlorine gas will react with the 4 moles of sodium.
Solution : Given,
Moles of sodium, (Na) = 4 moles
The given balanced chemical reaction is,

From the given balanced reaction, we conclude that
As, 2 moles of sodium(Na) react with 1 moles of chlorine gas

So, 4 moles of sodium(Na) react with
moles of chlorine gas

Therefore, 2 moles of chlorine gas will react with the 4 moles of sodium.