The P-Block Elements JEE 2025: Interhalogen Hydrolysis

What is the correct answer to the p-block elements JEE 2025 hydrolysis question?

Option A is correct: the corresponding oxyanions are hypoiodite, chlorite and bromate, in that order. This p-block elements JEE 2025 question is a single-correct MCQ from JEE Advanced 2025, Paper 2, Chemistry, not JEE Main.

The question bank rates it medium and gives an expected solving time of 90 seconds. This is the question bank’s practice benchmark, not an official exam time limit.

The task is to identify, in order, the oxyanions corresponding to complete hydrolysis of iodine monochloride, chlorine trifluoride and bromine pentafluoride:

I C l, C l F_{3}, B r F_{5}

I O^{-}, C l O_{2}^{-}, B r O_{3}^{-}

I O_{3}^{-}, C l O_{2}^{-}, B r O_{3}^{-}

I O^{-}, C l O^{-}, B r O_{2}^{-}

I O_{3}^{-}, C l O_{4}^{-}, B r O_{2}^{-}

The worked solution below derives each entry through balanced hydrolysis and acid dissociation. It does not assume the product list.

Why does iodine monochloride give hypoiodite?

Iodine monochloride forms hypoiodous acid, whose corresponding anion is hypoiodite. The official method starts with electronegativity: during interhalogen hydrolysis, the less electronegative central halogen usually forms an oxyacid, while the more electronegative halogen generally forms its hydrogen halide.

Chlorine is more electronegative than iodine. Assign chlorine to hydrogen chloride and iodine to hypoiodous acid: $I C l + H_{2} O \to H C l + H I O$

Atom check: each side contains one iodine, one chlorine, two hydrogen atoms and one oxygen atom. One water molecule supplies the hydrogen for both acids and the oxygen for hypoiodous acid.

Hypoiodous acid gives its corresponding anion through acid dissociation. Removing the acid’s hydrogen ion leaves hypoiodite:

\underset{hypoiodous acid}{\underset{⏟}{H I O}} ⇌ H^{+} + \underset{hypoiodite}{\underset{⏟}{I O^{-}}}

Hydrolysis and acid dissociation are separate steps. Complete hydrolysis does not mean complete acid dissociation: the options name the oxyacids’ corresponding anions, not every species present in solution.

Hydrogen chloride is also a hydrolysis product. Keep it in the equation to account for chlorine and hydrogen.

Why does chlorine trifluoride need two water molecules?

The three fluorine atoms require three hydrogen fluoride molecules. Including the oxyacid’s one hydrogen requires four hydrogen atoms, supplied by two water molecules.

Fluorine is more electronegative than chlorine, so it forms hydrogen fluoride while chlorine forms the oxyacid. For one mole of chlorine trifluoride, the water requirement is:

n (H_{2} O) = \frac{3 + 1}{2} = 2 m o l

Those two water molecules also supply two oxygen atoms. Both enter the oxyacid, giving chlorous acid:

C l F_{3} + 2 H_{2} O \to H C l O_{2} + 3 H F

Atom check: each side has one chlorine, three fluorine, four hydrogen and two oxygen atoms. Dissociation identifies the required ion:

\underset{chlorous acid}{\underset{⏟}{H C l O_{2}}} ⇌ H^{+} + \underset{chlorite}{\underset{⏟}{C l O_{2}^{-}}}

Chlorite contains two oxygen atoms. Do not confuse it with hypochlorite, which contains one:

\underset{hypochlorite}{\underset{⏟}{C l O^{-}}}

Why does bromine pentafluoride give bromate?

Bromine pentafluoride forms bromic acid, whose corresponding anion is bromate. Fluorine forms hydrogen fluoride, while the less electronegative bromine forms the oxyacid.

Five fluorine atoms require five hydrogen fluoride molecules. Including the oxyacid’s hydrogen gives six hydrogen atoms, supplied by three water molecules, which also provide three oxygen atoms:

B r F_{5} + 3 H_{2} O \to H B r O_{3} + 5 H F

Atom check: each side contains one bromine, five fluorine, six hydrogen and three oxygen atoms. The acid-to-anion step is:

\underset{bromic acid}{\underset{⏟}{H B r O_{3}}} ⇌ H^{+} + \underset{bromate}{\underset{⏟}{B r O_{3}^{-}}}

The ordered mappings connect each interhalogen to its oxyacid and corresponding anion. They are not complete reaction equations; the balanced equations above retain the hydrogen-halide coproducts.

Iodine monochloride: $I C l \to H I O \to I O^{-}$
Chlorine trifluoride:

C l F_{3} \to H C l O_{2} \to C l O_{2}^{-}

Bromine pentafluoride:

B r F_{5} \to H B r O_{3} \to B r O_{3}^{-}

In the question’s order, these anions match option A. Each oxygen count follows from the balanced hydrolysis equation.

Why is option B wrong?

Option B changes only the iodine product: A lists hypoiodite, while B lists iodate. The chlorine and bromine entries are identical.

If you choose iodate because iodic acid is familiar, you replace product derivation with recall of an unrelated formula. Use iodine’s oxidation state only to check the error:

I C l : & + 1 I O^{-} : & + 1 I O_{3}^{-} : & + 5

Replacing hypoiodous acid with iodic acid does not fit the balanced hydrolysis reaction shown. It would require additional redox chemistry absent from that solution.

Use the balanced-reaction method rather than an oxidation-state shortcut. Follow this correction sequence:

Assign the hydrogen halide using electronegativity.
Write and balance the oxyacid-forming reaction.
Identify the oxyacid’s corresponding anion.

Can you apply this method to three related interhalogens?

Use the same sequence: assign the hydrogen halide, balance water, then identify the corresponding anion. These are original related practice questions, not additional JEE PYQs; attempt each before checking its worked answer.

Which oxyacid and corresponding anion form when bromine monochloride undergoes hydrolysis?

Chlorine is more electronegative than bromine, so it forms hydrogen chloride. One water molecule supplies the remaining atoms for hypobromous acid: $B r C l + H_{2} O \to H B r O + H C l$ $H B r O ⇌ H^{+} + B r O^{-}$

The corresponding ion is hypobromite.

Complete and balance bromine trifluoride hydrolysis, then name its oxyanion.

Fluorine is more electronegative than bromine and forms hydrogen fluoride. Three hydrogen fluoride molecules plus the oxyacid’s hydrogen require two water molecules:

B r F_{3} + 2 H_{2} O \to H B r O_{2} + 3 H F

H B r O_{2} ⇌ H^{+} + B r O_{2}^{-}

The oxyacid is bromous acid, and its corresponding ion is bromite.

Which oxyacid and corresponding anion form from iodine pentafluoride hydrolysis?

Fluorine forms hydrogen fluoride because it is more electronegative than iodine. Five hydrogen fluoride molecules and one acid hydrogen require three water molecules:

I F_{5} + 3 H_{2} O \to H I O_{3} + 5 H F

H I O_{3} ⇌ H^{+} + I O_{3}^{-}

Here, iodic acid and iodate follow from the balanced reaction, whereas iodine monochloride gave hypoiodite. Cover these answers and reproduce all three equations, checking hydrogen and oxygen before naming each ion.

Next step: photograph a doubt on JEEnius and photograph any question you are stuck on and get a step-by-step solution, with a free-body diagram when the question needs one (20 free).

Frequently asked questions

What is the answer to the JEE Advanced 2025 interhalogen hydrolysis question?

Option A is correct: ICl, ClF3 and BrF5 give oxyacids whose corresponding anions are hypoiodite (IO−), chlorite (ClO2−) and bromate (BrO3−), respectively. This single-correct question is from JEE Advanced 2025, Paper 2, Chemistry.

Why does ICl hydrolysis give hypoiodite instead of iodate?

The balanced hydrolysis reaction is ICl + H2O → HCl + HIO, and HIO has hypoiodite (IO−) as its corresponding anion. Iodate would change iodine's oxidation state from +1 to +5, requiring additional redox chemistry absent from this solution.

Why are two water molecules needed for ClF3 hydrolysis?

Three fluorine atoms form three HF molecules, and the oxyacid requires one more hydrogen atom. Two water molecules supply these four hydrogen atoms and two oxygen atoms, giving ClF3 + 2H2O → HClO2 + 3HF.

Does complete hydrolysis mean complete acid dissociation?

No, hydrolysis and acid dissociation are separate steps. In this question, hydrolysis forms oxyacids, while the options identify their corresponding anions rather than every species present in solution.