See photo please. I need help on balancing equations.

A+b→2c when the reaction begins, the researcher records that the rate of reaction is such that 1 mole of a is consumed per minute. after making changes to the reaction, the researcher notes that 2 moles of a are consumed per minute. what change could the researcher have made to effect this change?

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

Can someone me with these questions plz.