Someone Help Me Plz. I'm not sure what the answer to this question is

H2so4(aq) + mg(s)—> mgso4(aq) +h2(g) which substance is the acid in the reaction?

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6