So in our hypothetical example, we have reactant AB, breaks down or decomposes into two new products, A plus B. Now let's look at a very common example. Now, the hydrolysis of water or the decomposition of water. In other words, two water molecules or two moles of H two in a liquid state react to produce 1 mol of O, two in a gas state, and two moles of diatomic H, two in the gas state. Now let's look at a third type and a fourth type of chemical reactions, namely single and double displacement. Now, single displacement reactions are also known as substitution reactions.