Question

What is the correct increasing order of Bronsted bases?
A) $Cl{{O}_{4}}^{-}$< $Cl{{O}_{3}}^{-}$< $Cl{{O}_{2}}^{-}$< $Cl{{O}^{-}}$
B) $Cl{{O}_{4}}^{-}$> $Cl{{O}_{3}}^{-}$> $Cl{{O}_{2}}^{-}$> $Cl{{O}^{-}}$
C) $Cl{{O}_{3}}^{-}$< $Cl{{O}_{4}}^{-}$< $Cl{{O}_{2}}^{-}$< $Cl{{O}^{-}}$
D) $Cl{{O}^{-}}$> $Cl{{O}_{3}}^{-}$> $Cl{{O}_{2}}^{-}$> $Cl{{O}_{4}}^{-}$

Answer 1

Hint: The Bronsted-Lowry theory, also known as the proton theory of acids and bases states that any compound that is able to transfer a proton to another compound is categorised as an acid, where a proton is considered as a nuclear particle with a unit positive electrical charge. On the contrary, the compound that receives a proton is known as a base. Similarly, on losing a proton, an acidic substance forms a base called the conjugate base of an acid while on gaining a proton, a basic substance forms an acid called the conjugate acid of a base. Keeping this in mind, we should be able to solve the given question.

Complete step by step answer:
We should know that Bronsted bases are the species which accept protons.
In the given options, oxygen is more electronegative than chlorine. Therefore, it will attract the electrons of chlorine atom more towards itself. As a result, the positive charge on chlorine atoms increases as the number of oxygen atoms increases.
Therefore, the probability to accept a proton will decrease. Thus, the basicity will also decrease with increase in oxygen atoms. So, the correct order of the Bronsted bases, in the increasing order is:
$Cl{{O}_{4}}^{-}$< $Cl{{O}_{3}}^{-}$< $Cl{{O}_{2}}^{-}$< $Cl{{O}^{-}}$
Therefore, the correct answer is Option A.

Note: Bronsted-Lowry Theory is very important to a chemist because, with this theory, one can observe and understand the chemical reactions occurring between acids and bases. It also shows how pH levels of various compounds are affected.