Which of the following is incorrect ?

Options

A. The transition metals react with halogens at elevated temperatures to form halids
B. The reactivity of halogens decreases in the order : `I_(2) gt Br_(2) gt CI_(2) gt F_(2)`
C. Metals are usually oxidized to their highest oxidation states to form fluorides
D. The lower oxidation states are stabilised in iodides.

Answer

B

Explanation

The reactivity of halogens decreases in the order,
`F_(2) gt CI_(2) gt Br_(2) gt I_(2)`
Bonding in fluorides is usually ionic. But the ionic character decreases in chlorides, bromides, and iodides with increasing mass of halogen. For example, `CuF_(2)` is an ionic compound while `CuCI_(2)` and `CuBr_(2)` are covalent forming infinite chains. On account of high active activation energies, high temperature is usually needed to stsrt the reaction between transition metals and halogen but once the reaction starts, the heat of reaction is sufficient to maintain the continuity of the reaction.