Correct order(s) is/are:

Options

A. Thermal stability: `H_(2)O gt H_(2)S gt H_(2) Se gt H_(2) Te`
B. Bond dissociation energy: `Cl_(2) gt Br_(2) gt F_(2) gt I_(2)`
C. Melting point: `NH_(3) gt SbH_(3) gt AsH_(3) gt PH_(3)`
D. `X-C-X` bond angle: `COCl_(2) gt COF_(2)`

Explanation

To solve the question regarding the correct orders of thermal stability, bond dissociation energy, melting point, and bond angles, we will analyze each property step by step.

### Step 1: Thermal Stability
- **Concept**: Thermal stability is directly proportional to bond strength and inversely proportional to bond length. As bond length increases, thermal stability decreases.
- **Analysis**: For the oxygen family (O, S, Se, Te), as we move down the group, the size of the atoms increases, leading to an increase in bond length and a decrease in thermal stability.
- **Order**: The correct order of thermal stability is:
\[ \text{S}_2\text{O} < \text{S}_2\text{S} < \text{S}_2\text{Se} < \text{S}_2\text{Te} \]

### Step 2: Bond Dissociation Energy
- **Concept**: Bond dissociation energy is also dependent on bond strength and bond length. Generally, as we move down a group, bond dissociation energy decreases due to increasing bond length.
- **Exception**: Fluorine has lower bond dissociation energy than chlorine and bromine due to increased electron-electron repulsion in F₂.
- **Order**: The correct order of bond dissociation energy for halogens (F, Cl, Br, I) is:
\[ \text{Cl}_2 > \text{Br}_2 > \text{F}_2 > \text{I}_2 \]

### Step 3: Melting Point
- **Concept**: Melting point is directly proportional to the strength of interatomic forces. Hydrogen bonding significantly increases melting points compared to Van der Waals forces.
- **Analysis**: NH₃ has a higher melting point due to hydrogen bonding, while SbH₃, AsH₃, and PH₃ have lower melting points due to Van der Waals forces, which depend on molecular weight.
- **Order**: The correct order of melting points is:
\[ \text{NH}_3 > \text{SbH}_3 > \text{AsH}_3 > \text{PH}_3 \]

### Step 4: Bond Angles
- **Concept**: The bond angle is influenced by the size of the surrounding atoms. Larger atoms lead to larger bond angles.
- **Analysis**: In COCl₂, chlorine is larger than fluorine, leading to a larger bond angle compared to COF₂.
- **Order**: The correct order of bond angles is:
\[ \text{Bond angle in COCl}_2 > \text{Bond angle in COF}_2 \]

### Summary of Correct Orders
1. **Thermal Stability**: \(\text{S}_2\text{O} < \text{S}_2\text{S} < \text{S}_2\text{Se} < \text{S}_2\text{Te}\)
2. **Bond Dissociation Energy**: \(\text{Cl}_2 > \text{Br}_2 > \text{F}_2 > \text{I}_2\)
3. **Melting Point**: \(\text{NH}_3 > \text{SbH}_3 > \text{AsH}_3 > \text{PH}_3\)
4. **Bond Angles**: \(\text{Bond angle in COCl}_2 > \text{Bond angle in COF}_2\)