Intermolecular hydrogen bonding is strongest in

Options

A. Methylamine
B. Phenol
C. Formaldehyde
D. Methanol

Explanation

To determine which compound exhibits the strongest intermolecular hydrogen bonding among the given options (methyl amine, phenol, formaldehyde, and methanol), we can follow these steps:

### Step 1: Identify the functional groups in each compound
- **Methyl amine (CH₃NH₂)**: Contains an NH group.
- **Phenol (C₆H₅OH)**: Contains an OH group attached to an aromatic ring.
- **Formaldehyde (HCHO)**: Contains a carbonyl group (C=O) but does not have an OH group.
- **Methanol (CH₃OH)**: Contains an OH group.

### Step 2: Understand the nature of hydrogen bonding
Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (like N, O, or F) and interacts with another electronegative atom. The strength of hydrogen bonding increases with the electronegativity of the atom bonded to hydrogen.

### Step 3: Compare the electronegativities
- **Oxygen (O)** is more electronegative than **Nitrogen (N)**.
- Therefore, OH bonds (as in phenol and methanol) will generally form stronger hydrogen bonds than NH bonds (as in methyl amine).

### Step 4: Analyze the compounds
- **Methyl amine**: NH bond can form hydrogen bonds, but they are weaker compared to OH bonds.
- **Phenol**: The OH group can form hydrogen bonds, but the presence of the aromatic ring may affect the strength.
- **Formaldehyde**: While it has a polar C=O bond, it does not have an OH group, so it cannot form hydrogen bonds as effectively.
- **Methanol**: The OH group is present, and since it is not hindered by an aromatic ring, it can form strong hydrogen bonds.

### Step 5: Conclusion
Comparing the hydrogen bonding capabilities:
- Methanol (CH₃OH) has a strong OH bond and can form extensive hydrogen bonding.
- Phenol also has an OH bond but is less effective due to the aromatic ring.
- Methyl amine has NH bonds which are weaker than OH bonds.
- Formaldehyde lacks an OH group and thus cannot participate in hydrogen bonding as effectively.

Therefore, the compound with the strongest intermolecular hydrogen bonding is **Methanol**.

### Final Answer:
**Methanol**