The order of thermal stability of hydrides of group 16 elements is?

Options

A. `H_(2)O gt H_(2)S gt H_(2)Se gt H_(2) Te gt H_(2)PO`
B. `H_(2)O lt H_(2)S gt H_(2) Se gt H_(2)Te gt H_(2)PO`
C. `H_(2)O gt H_(2)Se gt H_(2)Te gt H_(2)S gt H_(2)PO`
D. `H_(2)PO gt H_(2)S gt H_(2)Te gt H_(2)Se gt H_(2)O`

Explanation

To determine the order of thermal stability of hydrides of group 16 elements, we will analyze the hydrides: H2O, H2S, H2Se, and H2Te.

### Step-by-Step Solution:

1. **Identify the Hydrides**: The hydrides of group 16 elements are H2O (water), H2S (hydrogen sulfide), H2Se (hydrogen selenide), and H2Te (hydrogen telluride).

2. **Understand Bond Strength**: The thermal stability of these hydrides is influenced by the strength of the bonds between hydrogen and the group 16 element. Stronger bonds result in higher thermal stability.

3. **Analyze Bond Lengths**: As we move down the group from oxygen to tellurium, the size of the central atom increases. This increase in size leads to longer bond lengths between hydrogen and the central atom.

4. **Relate Bond Length to Bond Strength**: Longer bond lengths generally correspond to weaker bonds. Therefore, as we go from H2O to H2Te, the bond strength decreases.

5. **Order of Thermal Stability**: Since H2O has the strongest bond (shortest bond length) and H2Te has the weakest bond (longest bond length), we can conclude that the thermal stability decreases in the following order:
- H2O > H2S > H2Se > H2Te

6. **Final Conclusion**: The order of thermal stability of the hydrides of group 16 elements is:
- H2O > H2S > H2Se > H2Te