The forces of cohesion in liquid helium are

Options

A. covalent
B. ionic
C. van der waals
D. metallic

Answer

To determine the forces of cohesion in liquid helium, we can analyze the nature of helium and the types of bonding that can occur.

### Step-by-Step Solution:

1. **Identify the Nature of Helium**:
- Helium is a noble gas with the electronic configuration of \(1s^2\). This means it has a complete outer shell of electrons, making it chemically inert.

**Hint**: Remember that noble gases have full valence shells, which influences their bonding behavior.

2. **Evaluate Covalent Bonds**:
- Covalent bonds involve the sharing of electrons between atoms. Since helium has a complete outer shell, it does not have the ability to share electrons with other helium atoms.

**Hint**: Consider how electron sharing works and why it’s not applicable to helium.

3. **Evaluate Ionic Bonds**:
- Ionic bonds are formed when one atom donates electrons to another, resulting in charged ions. Helium cannot donate or accept electrons due to its stable electron configuration.

**Hint**: Think about the stability of noble gases and their reluctance to gain or lose electrons.

4. **Evaluate Metallic Bonds**:
- Metallic bonds occur between metal atoms where electrons are shared in a "sea" of electrons. Helium is not a metal and cannot form metallic bonds with other helium atoms.

**Hint**: Recall the characteristics of metallic bonding and why they do not apply to non-metals like helium.

5. **Identify Van der Waals Forces**:
- The only type of cohesive force that can exist between helium atoms in liquid form is van der Waals forces. These are weak intermolecular forces that arise due to temporary dipoles formed when electron distributions around atoms fluctuate.

**Hint**: Consider the nature of van der Waals forces and how they differ from stronger bonds like covalent and ionic.

6. **Conclusion**:
- Therefore, the forces of cohesion in liquid helium are primarily van der Waals forces.

### Final Answer:
The forces of cohesion in liquid helium are **van der Waals forces**.