Questions about theoretical yield?

its a simple question that concerns your knowledge regarding moles,molecular masses and limiting reagents

In Q.1. if u see the equation u will realise that the reagent having a low molecular mass is water as compared to PCl3 and its required amount as compared to the latter is low to form the products and if u jus go by common sense then u cn see that the amount of water required is stoichometrically equal to amount of HCl formed.

So u need not go into calculating it as it is very much visible.

Bt to make u understand better, i have done the calculations as well ;-

Since water is the limiting reagent in this equation,we can deduce that 3 moles of water form 3 moles of hydrochloric acid

So,7.18 moles will form as much moles of HCl

Q.2. Here the limiting reagent is PF3 and not XeF4( it has higher molar mass)

46 * 2 gms of PF3 yields ------------------> 64 *2 gm of PF5

5.39 gms will help form ---------------> 64/46 * 5.39

---------------> 7.499 gms of PF5

Hope this answers your question and in case u have any queries u cn get in touch in touch with me,I'll be more than happy to help u out.