Answer:
a) 1.61 mol
b) Al is limiting reactant
c) HBr is in excess
Step-by-step explanation:
Given data:
Moles of Al = 3.22 mol
Moles of HBr = 4.96 mol
Moles of H₂ formed = ?
What is limiting reactant = 
What is excess reactant = ?
Solution:
Chemical equation:
2Al + 2HBr → 2AlBr + H₂
Now we will compare the moles:
 Al : H₂ 
 2 : 1
 3.22 : 1/2×3.22 = 1.61 mol
 HBr : H₂ 
 2 : 1
 4.96 : 1/2×4.96 = 2.48 mol 
The number of moles of H₂ produced by Al are less it will be limiting reactant while HBr is present in excess. 
Moles of H₂ :
Number of moles of H₂ = 1.61 mol