Question

Formation of water is reversible change. Identify the chemical formula of formation of water.
A) $$H_2+2O_2\to 2H_{2}O$$
B) $$2H_2+O_2\to H_{2}O$$
C) $$H_2+O_2\to H_{2}O$$
D) $$2H_2+O_2\to 2H_{2}O$$

Answer 1

Hint: We must have to remember that the reversible process is the one which can be reversed. Hydrogen and oxygen atoms react together to form water. And if electric current is applied, the water molecule breaks itself into hydrogen gas and oxygen. Irreversible process is the one which cannot be reversed.

Complete answer:
We need to balance the chemical equation in order to get a complete chemical equation. A balanced chemical equation is the one in which the number of moles for each element is same in both the reactant side and product side or you can say that the number of moles should be equal in both left hand side and right hand side. We will look at all the options one by one.
Option A) this is an incorrect option as the number of oxygen atoms in the left hand side is four whereas in the right hand side is two thus this is not a balanced chemical equation.
Option B) This is an incorrect option and the number of hydrogen in the left hand side is four whereas in the right hand side its two thus this does not define a balanced equation.
Option C) this is an incorrect option as oxygen atoms in the left hand side are not balancing the one in the right hand side thus this equation is not a balanced equation.
Option D) this option is correct as this chemical equation $$2H_2+O_2\to 2H_{2}O$$ represents a complete balanced equation as the number of atoms for hydrogen and oxygen is same in both left and right hand side.

Note:
We have to remember that a chemical equation is said to complete if it is balanced, balancing is required in the atoms that are present in reactants and products. Reactants react in a way to form a product. Also note that formation of water is a reversible process.