Question

Which one of the following is a strong base?
A. ${{NaOH}}$
B. ${{CsCl}}$
C. ${{HBr}}$
D. ${{C}}{{{H}}_3}{{COOH}}$
E. ${{{O}}_2}$

Answer 1

Acids and bases are defined using three basic theories, i.e. Arrhenius concept, Lewis theory and Lowry-Bronsted concept. Generally bases have a bitter taste and have a slippery nature. The strength of bases is dependent on the extent of ionization.

Complete step by step answer:
Acids are the compounds which have the ability to give hydrogen ions or protons. In another way, it can also be defined as the compounds which have the ability to accept electrons.
While bases are the compounds which have the ability to accept hydrogen ions or protons. It can also be defined as the compounds which have the ability to give out electrons.
Generally, we can say that the strong bases are produced from alkali metals hydroxides and alkaline earth metal hydroxides.
The strength of bases can be determined using base-ionization constant, ${{{K}}_{{b}}}$ in their aqueous solutions. Strong bases, generally, ionize to a greater extent. Strong bases have larger value of ionization constant while weak bases have lower value of ionization constant.
From the given options, ${{NaOH}}$ dissociates completely in solution into sodium ion and hydroxide ion. But ${{CsCl}}$ is a salt. ${{HBr}}$ can be included in the family of ${{HCl}}$ which is a strong acid since it can give out a hydrogen ion or proton. And ${{C}}{{{H}}_3}{{COOH}}$ is a weak acid. It does not dissociate completely into its constituent ions. Oxygen molecule is not an acidic compound or basic compound. Thus it can be considered neutral.
Hence we can say that ${{NaOH}}$ is a strong base.

So, the correct option is A.

Note: The strength of acid can also be determined using the ${{pH}}$ value. ${{pH}}$ value ranges from $0 - 14$ in which acids belong to those with ${{pH}}$ value less than $7$ and bases belong to those with ${{pH}}$ value greater than $7$. Strong bases have ${{pH}}$ values ranging from $12$ to $14$.