A chemical reaction is in which the bonds are broken within reactant molecules, and new bonds are formed within product molecules in order to form a new substance. Balancing chemical equation refers to balancing the stoichiometric coefficients on the reactants and products side. This must be done as the chemical equation obeys the law of conservation of mass and momentum.
(a) Mg(s) + Cl2(g) → MgCl2(s)
Mg(s) + Cl2(g) → MgCl2(s)
This type of reaction is called a combination reaction or a synthesis reaction.
(b) HgO(s) (Heat)→ Hg(l) + O2(g)
2HgO(s) (Heat) → 2Hg(I) + O2(g)
This is an example of a thermal decomposition reaction.
(c) Na(s) + S(s) (Fuse) → Na2S(s)
2Na(s) + S(s)(Fuse) → Na2S(s)
This is an example of a Combination reaction.
(d) TiCl4 (l) + Mg(s) → Ti(s) + MgCl2(s)
TiCI4 (l) + 2Mg(s) → Ti(s) + 2MgCl2 (s)
This reaction falls under the category of Displacement reactions
(e) CaO(s) + SiO2 (s) → CaSiO3(s)
Above reaction is a combination reaction.
(f) 2H2O2(l)(UV) → 2H2O(l) + 2O2(g)
Above reaction is decomposition reaction.