Thermal stability of hydrides of group-16 elements decreases down the group. Why?
Why `ICl` is more reactive than `I_(2)` ?

Explanation

### Step-by-Step Solution

**1. Understanding the Thermal Stability of Hydrides in Group 16:**
- The hydrides of group 16 elements include H2O (water), H2S (hydrogen sulfide), H2Se (hydrogen selenide), H2Te (hydrogen telluride), and H2Po (hydrogen polonide).
- As we move down the group from oxygen to polonium, the size of the central atom (M) increases. This increase in atomic size leads to a decrease in the bond strength of the M-H bond.

**2. Bond Dissociation Energy:**
- The bond dissociation energy (BDE) refers to the energy required to break a bond between two atoms. For the hydrides of group 16, the bond dissociation energy decreases as we go down the group.
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