Answer:
0.3 mol A is combined with 0.8 mol B.
Explanation:
Limiting reagent in a chemical reaction is defined as the reagent that is totally consumed when the chemical reaction is complete.
In the reaction:
A + 2B → 2C+D
For a reaction of 1 mole of A, you need two moles of B. That means for any quantity of A you need twice this quantity in B.
Thus, A is limiting reagent when moles of B are higher than twice moles of A.
* 0.5 mol A is combined with 0.3 mol B. Twice moles of A are 1.0 moles that are higher than 0.3 moles. A is not limitng reagent.
* 0.5 mol A is combined with 0.6 mol B. Twice moles of A are 1.0 moles that are higher than 0.6 moles. A is not limitng reagent.
* 0.2 mol A is combined with 0.3 mol B. Twice moles of A are 0.4 moles that are higher than 0.3 moles. A is not limitng reagent.
* 0.3 mol A is combined with 0.8 mol B. Twice moles of A are 0.6 moles that are lower than 0.8 moles. A IS limitng reagent.
I hope it helps!