Which of the following order is incorrect?

Options

A. Lewis basic character: `NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3)`
B. Bond dissociation energy `HF gt HCl gt HBr gt HI`
C. Thermal stability: `H_(2) O gt H_(2)S gt H_(2)Se gt H_(2) Te`
D. Bond angle: `CH_(4) gt SiH_(4) gt GeH_(4) gt SnH_(4)`

Answer

To determine which of the given orders is incorrect, we will analyze each option step by step.

### Step 1: Analyze the Lewis Basic Character
**Order Given:** NH3 > PH3 > AsH3 > SbH3

- **Explanation:** The Lewis basic character is influenced by the size of the atom. Smaller atoms have more localized lone pairs, making them better Lewis bases.
- **Conclusion:** This order is correct because NH3 has the smallest size and thus the most localized lone pair, making it the strongest Lewis base.

### Step 2: Analyze the Bond Dissociation Energy
**Order Given:** HF > HCl > HBr > HI

- **Explanation:** As we move down the group in the periodic table, the bond length increases due to larger atomic sizes. Longer bonds are generally weaker and have lower bond dissociation energies.
- **Conclusion:** This order is correct because HF has the shortest bond length and thus the highest bond dissociation energy.

### Step 3: Analyze the Thermal Stability
**Order Given:** H2O > H2S > H2Se > H2Te

- **Explanation:** Similar to bond dissociation energy, as the bond length increases down the group, the bond becomes weaker, leading to decreased thermal stability.
- **Conclusion:** This order is correct because H2O has the strongest bond and therefore the highest thermal stability.

### Step 4: Analyze the Bond Angle Comparison
**Order Given:** CH4 > SiH4 > GeH4 > SnH4

- **Explanation:** All these molecules have a tetrahedral geometry with a bond angle of approximately 109.5 degrees. The bond angles do not significantly change among these molecules.
- **Conclusion:** This order is incorrect because all the bond angles are essentially equal, making it a false comparison.

### Final Answer
The incorrect order is the bond angle comparison: **CH4 > SiH4 > GeH4 > SnH4**.

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