The incorrect order of decreasing boiling point is

Options

A. `HF gt HI gt HBr gt HCl`
B. `H_2O gt H_2Te gt H_2Se gt H_2S`
C. `Br_2 gt Cl_2 gt F_2`
D. `CH_4 gt GeH_4 gt SiH_4`

Explanation

To determine the incorrect order of decreasing boiling points among the given molecules (HF, HI, HBr, HCl), we need to analyze the boiling points based on the types of intermolecular forces present and the molecular weights of the compounds.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Intermolecular Forces:**
- HF (Hydrogen Fluoride): Exhibits strong hydrogen bonding due to the highly electronegative fluorine atom.
- HCl (Hydrogen Chloride): Exhibits dipole-dipole interactions and some hydrogen bonding, but weaker than HF.
- HBr (Hydrogen Bromide): Similar to HCl but with a larger molecular size, leading to weaker dipole-dipole interactions.
- HI (Hydrogen Iodide): Exhibits weaker dipole-dipole interactions compared to HBr and HCl due to larger size and lower electronegativity of iodine.

2. **Analyze the Boiling Points:**
- HF has a significantly higher boiling point due to strong hydrogen bonding.
- HCl has a lower boiling point than HF but higher than HBr and HI.
- HBr has a lower boiling point than HCl but higher than HI.
- HI has the lowest boiling point among these due to the weakest intermolecular forces.

3. **Order the Compounds by Boiling Points:**
- The expected order of boiling points from highest to lowest is:
- HF > HCl > HBr > HI

4. **Identify the Incorrect Order:**
- If we consider the options provided, any order that suggests HI has a higher boiling point than HBr, HCl, or HF would be incorrect.
- For example, if an option states HI > HBr > HCl > HF, this would be the incorrect order of decreasing boiling points.

### Conclusion:
The incorrect order of decreasing boiling point among the options provided is likely to be one that places HI above HBr, HCl, or HF.