An atom with high electronegativity has

Options

A. Large size
B. low electron affinity
C. High ionisation enthalpy
D. Low chemical reactivity.

Explanation

To solve the question "An atom with high electronegativity has," we need to analyze the given options and understand the relationship between electronegativity and other atomic properties.

### Step-by-Step Solution:

1. **Understanding Electronegativity**:
- Electronegativity is the ability of an atom to attract electrons in a chemical bond. Atoms with high electronegativity tend to attract electrons more strongly.

2. **Analyzing the Options**:
- **Option 1: Large Size**:
- Electronegativity increases across a period in the periodic table. As you move from left to right, atomic size decreases. Therefore, an atom with high electronegativity cannot have a large size. **This option is incorrect.**

- **Option 2: Low Electron Affinity**:
- Atoms with high electronegativity have a strong tendency to attract electrons, which means they have high electron affinity (the energy change when an electron is added). Thus, this option is also incorrect.

- **Option 3: High Ionization Enthalpy**:
- Ionization enthalpy is the energy required to remove an electron from an atom. For atoms with high electronegativity, it is generally more difficult to remove an electron because they hold onto their electrons more tightly. Therefore, they exhibit high ionization enthalpy. **This option is correct.**

- **Option 4: Low Chemical Reactivity**:
- Atoms with high electronegativity are more reactive because they can easily gain electrons. Therefore, this statement is incorrect as well.

3. **Conclusion**:
- The correct answer is that an atom with high electronegativity has **high ionization enthalpy**.

### Final Answer:
An atom with high electronegativity has **high ionization enthalpy**.

---