Question

Identify the limiting reagent in the reaction mixture shown below (red = a2, blue = b2). the balanced reaction is a2+2b2→2ab2

Answer 1

With the equation A₂+2B₂→2AB₂ we know that one mole of A₂ is necessary to react with two moles of B₂ and with that, we obtain two moles of the product. ( you can see this by just seeing what numbers are before the letters)

Since it's needed more quantity of B than A,  B is the limited reagent.