The correct structure of perchloric acid is :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → HClO4 with one Cl–OH and three Cl=O bonds
Perchloric acid, \( \ce{HClO4} \), is the oxoacid of chlorine in the +7 oxidation state. Chlorine is bonded to four oxygen atoms: one –OH group and three oxygens joined by Cl=O double bonds, the four oxygens arranged tetrahedrally round Cl. Structure (1) shows this arrangement.
Why the other options are incorrect
Option (2) — Incorrect. All three oxygens are joined by single bonds; perchloric acid has three Cl=O bonds.
Option (3) — Incorrect. Only two Cl=O double bonds are shown, with the third oxygen singly bonded; this does not match the structure with three Cl=O bonds.
Option (4) — Incorrect. Again only two Cl=O double bonds and one singly bonded oxygen, drawn in a different position; it does not match the structure of perchloric acid.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.