6Al + 18HCl -> 6AlCl3 + 9H2
so we have 6mols of Al and 13 moles of HCl
but the equation says we need 18 moles
so HCl is going to run out first
now we need to work out how many moles of Al will react with 13 moles of HCl
so use your equation to figure that out and then you'll get the moles of Al you have and then use your equation to fnd out how many moles of H2 you will get.
7) balance the equation. seriously. it's not that hard
find the moles of both of them and then just follow the question in 6, find the limiting reagent, find how much will react with that limiting reagent, use that to calc moles of MgO from the equation and then times it by the molar mass
I seriously suggest that you drop out of chemistry if you are having this much trouble with it or consider getting a tutor because it only gets harder and you are not doing yourself any good by not doing these questions and just getting the answers off the internet. Some of these are pretty simple so either you didn't bother doing them or you are having genuine trouble. Either way, get help from your teacher....