Question

On hydrolysis of an interhalogen compound, oxyhalide ion is formed from:
A. Larger halogen
B. Smaller halogen
C. Both halogens
D. More electronegative halogen

Answer 1

Hint: Molecules of interhalogen compounds have two halogen atoms of different electronegativities and sizes. The oxyhalide ion is formed by the less electronegative halogen atom. By knowing the relation between size and electronegativity, we can figure out the size of the atom that forms the oxyhalide ion.

Complete Step by Step Solution:
An interhalogen compound is formed by the reaction of halogens with each other. Molecules of interhalogen compounds contain two or more different halogen atoms and no atoms of any other group. The chemical formulae for interhalogen compounds are generally \[XX{'_n}\] where \[n = 1,3,5{\rm{ or 7}}\]. X represents the halogen that is comparatively less electronegative (and larger in size) and X’ represents the more electronegative halogen (which is smaller in size). Examples of interhalogen compounds include bromine monochloride (\[BrCl\]), chlorine trifluoride (\[Cl{F_3}\]), iodine pentafluoride (\[I{F_5}\]) etc.
The number of atoms per molecule increases with the radius ratio of X and X’ atoms.
They are all volatile solids or liquids at STP except chlorine monofluoride (\[ClF\]) which is a gas.

Interhalogen compounds are generally more reactive than diatomic halogen compounds (except fluorine gas). This is because the X-X’ bond in interhalogens is weaker than the X-X bond in diatomic halogens. The chemical reactions of interhalogen compounds are comparable to halogens.

All interhalogen compounds are prone to hydrolysis. Hydrolysis of interhalogen compounds yields a hydrogen halide and an oxyhalide. The hydrogen halide is derived from the smaller halogen atom and the oxyhalide is derived from the larger halogen atom.
\[XX' + {H_2}O(l) \to HX'(aq) + HOX(aq)\]
As an example, consider the hydrolysis of iodine monochloride (\[ICl\]). In this molecule, iodine is the larger atom and chlorine is the smaller atom. Thus, the oxychloride formed will be derived from the iodine atom and the chlorine atom will form hydrogen chloride as shown below:
\[ICl(s) + {H_2}O(l) \to HCl(aq) + HOI(aq)\]

Thus, option A is correct.

Additional information:
The compound formed alongside hydrogen halide differs according to the type of interhalogen compound (value of n in the general formula \[XX{'_n}\]).

Value of n	Compound formed
1	Hypohalite (\[HOX\])
3	Halite (\[HOXO\])
5	Halate (\[HOX{O_2}\])
7	Perhalate (\[HOX{O_3}\])

Note: This is a factual question which means there is only a single correct answer here. These types of questions become impossible to solve if the facts are not known beforehand. Thus, it is recommended that the student has adequate knowledge of facts like this.