Question

what happens aluminium is heated with conc. h2so4

Answer 1

Aluminium reacts with hot, concentrated sulphuric acid to form aluminium sulphate with the evolution of sulphur dioxide gas. Sulphuric acid acts an oxidising agent, and gets itself reduced to SO2.

                             2Al + 6H2SO4 = Al2(SO4)3 + 3SO2 + 6H2O

Only with the dilute acid, the metal liberates hydrogen gas.

Answer 2

Al +H2SO4=Al2(SO4)3+H2

hydrogen would be released