B. 538 j hoped this helps
Answer:

Explanation:
Combination reactions are the reactions in which two or more atoms/ molecules combine to give a single product.
Aluminum metal combines with iodine to given aluminium iodide.
Aluminium has a valency of 3 and iodine has valency of 1, so the formula is 
The reaction is shown below as:

Answer:
P₄ + 5O₂ → 2P₂O₅
Explanation:
Phosphorus burn in the presence of air and produced diphosphorus pentoxide.
Chemical equation:
P₄ + O₂ → P₂O₅
Balanced chemical equation:
P₄ + 5O₂ → 2P₂O₅
Equation is balanced because there are four phosphorus atoms ans ten oxygen atoms in both side of equation.
Coefficient with reactant and product:
P₄ 1
O₂ 5
P₂O₅ 2
(2) Mg, Ca, and Ba have the most similar chemical properties, and we know this because of their coexistence in the group alkali earth metals (group 2) on the periodic table.
I’m not totally sure but I think the answer is B