I think the solution given is wrong so just wanted to confirm…
Bro i’m not getting the first question.
But to answer you rsecond question, Cl2 is given as thrice of Br2. Hence we do not have to consider volumes. In the sense that we have already factored in volume by multiplying 3 to the no.of moles of bromine.
For the 1st question can you ask your sir how to solve it??