Answer:
(a)
(b) 
Explanation:
The reaction that is carried out by the enzyme catalase produces
The reaction that is carried out by the enzyme catalase produces 
Answer:- HBr is limiting reactant.
Solution:- The given balanced equation is:

From this equation, There is 2:6 mol or 1:3 mol ratio between Al and HBr. Since we have 8 moles of each, HBr is the limiting reactant as we need 3 moles of HBr for each mol of Al.
The calculations could be shown as:

= 24 mol HBr
From calculations, 24 moles of HBr are required to react completely with 8 moles of Al but only 8 moles of it are available. It clearly indicates, HBr is limiting reactant.
Answer:
11
Explanation:
3 + 8 = 11
20 character minimum, here you go.
The reactant is the chemical reaction of 2 or more different elements.
The product is what is formed in a chemical reaction.
Example: H + O ----> H2O
H + O is the reactants, and H2O is the products.
Answer:
Atomic number is the number of protons in an isotope or element.
Explanation: The atomic number is the same number of protons in an element or isotope and if said isotope is neutral than it is the same number of electrons.
Example: Atomic number = 19 Protons = 19 if neutral Electrons = 19