Aluminum plus chlorine yields aluminum chloride

Well , first you write the formulas of the reactants and the reaction products. and then you balance the equation, making sure the number of atoms of each substance that appear among the reactants is the same that is in the reaction products. 

here it goes.. 

Hydrogen plus Oxygen yield water. 
2H2+ O2--> 2H2O 

Nitrogen plus hydrogen yield ammonia. 
N2+2H2-->2NH4 

Aluminum bromide plus chlorine yield aluminum chloride and bromine. 
2AlBr3+ 3Cl2--> 2AlCl3+3Br2 

Hydrochloric acid plus sodium hydroxide yield sodium chloride plus water. 
HCl+NaOH-->NaCl+H2O 

Iron plus Lead(2) sulfate react forming iron(2) sulfate plus lead. 
Fe+ PbSO2-->FeSO2+2Pb 

Potassium chlorate when heated produces potassium chloride plus oxygen gas. 
KClO3---> KCl+ 3/2O2 

Sulfuric acid decomposes to form sulfur trioxide gas plus water. 
H2SO4-->SO3+H2O 

Sodium oxide combines with water to make sodium hydroxide. 
Na2O+H2O-->2NaOH 

Potassium iodide reacts with bromine forming potassium bromide plus 
2KI+ BR2--> 2KBr+ I2

Answer:

a. energy is absorbed in the reaction.

explanation:

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.