Which among the following is the most reactive?
(B) In general interhalogen compounds are more reactive than halogens (except fluorine). ICℓ is interhalogen compounds.
To determine which among the given substances is the most reactive, we need to understand the concept of reactivity in halogens. Halogens are elements in Group 17 of the periodic table, and their reactivity decreases down the group. This is because atomic size increases down the group, making it harder to gain an electron (which is what makes them reactive).
The order of reactivity for halogens is: F2 > Cl2 > Br2 > I2. Since F2 is not an option, among the given choices, Cl2 is the most reactive.
ICℓ is not a pure halogen but an interhalogen compound (iodine monochloride), and its reactivity is generally lower than that of Cl2.
Reactivity Trend in Halogens: Reactivity decreases down the group due to increasing atomic radius and decreasing electron gain enthalpy.
Electron Gain Enthalpy: It is the energy released when an electron is added to a neutral atom. Halogens have high electron gain enthalpy, which decreases down the group.
Interhalogen Compounds: Compounds formed between two different halogens (e.g., ICℓ). They are generally less reactive than the parent halogens.