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Question:

What is the correct increasing order of Bronsted bases?

ClO⁻₄<ClO⁻₃<ClO⁻₂<ClO⁻

ClO⁻₄>ClO⁻₃>ClO⁻₂>ClO⁻

ClO⁻₃<ClO⁻₄<ClO⁻₂<ClO⁻

ClO⁻>ClO⁻₃>ClO⁻₂>ClO⁻₄

Solution:

The correct option is ClO⁻₄<ClO⁻₃<ClO⁻₂<ClO⁻. ClO⁻₄<ClO⁻₃<ClO⁻₂<ClO⁻ is the correct increasing order of Bronsted base strength. With an increase in the number of oxygen atoms, the extent of delocalisation of negative charge by pπ-dπ bonding increases. This stabilizes the ion and decreases the tendency to accept a proton. This decreases the basicity.