Question

Give one example each of displacement, decomposition and combination reaction with explaination.

Answer 1

Displacement reaction :
A single-displacement reaction, also known as a single-replacement reaction, is a reaction by which one
(or more) element(s) replaces an/other element(s) in a compound. It can be represented generally as:
$A+B-C\to A-C+B$
All simple metal with acid reactions are single displacement reactions. For example, the reaction
between magnesium, $Mg$, and hydrochloric acid, $HCl$, forms magnesium chloride, $MgC{l}_2$, and hydrogen,
$H_2$.
$Mg\left(s\right)+2HCl\left(aq\right)\to MgC{l}_2\left(aq\right)+H_2\left(g\right)$
Decomposition reaction :
A decomposition reaction is a type of chemical reaction where one reactant yields two or more
products.
The general form for a decomposition reaction is
$AB\to A+B$
Water can be separated by electrolysis into hydrogen gas and oxygen gas through the decomposition
reaction: $2H_{2}O\to 2H_2+O_2$
Another example is the spontaneous decomposition of hydrogen peroxide into water and oxygen: 2
$H_2{O}_2\to 2H_{2}O+O_2$
The decomposition of potassium chlorate into potassium chloride and oxygen is yet another example:
$2KCl{O}_3\to 2KCl+3O_2$
Combination reaction :
A combination reaction (also known as a synthesis reaction) is a reaction where two or more elements
or compounds (reactants) combine to form a single compound (product). Such reactions may be
represented by equations of the following form : $X+Y\to XY$.
Formation of calcium oxide by the combination elements calcium and oxygen.
$2Ca+O_2\to 2CaO$
Formation of ammonia by the combination of elements nitrogen and hydrogen.
$N_2+3H_2\to 2N{H}_3$