Which is true statement(s)?

Options

A. Large is the value of ionisation enthalpy easier is the formation of cation.
B. Larger is the value of electron gain enthalpy, easier is the formation of anion.
C. Large is the have of ionisation energy as well as electron affinity, smaller is the Muliken electronegativity of atom.
D. Large to the `Z_(eff)` large is the size of atom.

Explanation

To determine which of the statements provided is true, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** "Largest is the value of ionization enthalpy, easier is the formation of cation."

**Analysis:**
- Ionization enthalpy refers to the energy required to remove an electron from an isolated gaseous atom.
- If the ionization enthalpy is large, it means a significant amount of energy is needed to remove an electron.
- Therefore, a high ionization enthalpy makes it more difficult to form a cation because more energy is required to remove the electron.

**Conclusion:** This statement is **false**.

### Step 2: Analyze the second statement
**Statement:** "Large is the value of electron gaining enthalpy, easier is the formation of anion."

**Analysis:**
- Electron gain enthalpy is the energy released when an electron is added to an isolated gaseous atom.
- A larger (more negative) electron gain enthalpy indicates that it is easier to add an electron to the atom.
- Hence, a large value of electron gain enthalpy indeed facilitates the formation of an anion.

**Conclusion:** This statement is **true**.

### Step 3: Analyze the third statement
**Statement:** "Larger is the ionization energy as well as electron affinity, smaller is the mollican electronegativity of an atom."

**Analysis:**
- According to the Mulliken scale, electronegativity is calculated as the average of ionization energy and electron affinity.
- If both ionization energy and electron affinity are large, the average (and thus the electronegativity) will also be large.
- Therefore, a larger ionization energy and electron affinity would lead to a larger Mulliken electronegativity.

**Conclusion:** This statement is **false**.

### Step 4: Analyze the fourth statement
**Statement:** "Large is the effective nuclear charge. Large is the size of that atom."

**Analysis:**
- Effective nuclear charge refers to the net positive charge experienced by valence electrons.
- As the effective nuclear charge increases, the attraction between the nucleus and the valence electrons becomes stronger, pulling the electrons closer to the nucleus.
- This results in a decrease in atomic size, not an increase.

**Conclusion:** This statement is **false**.

### Final Conclusion
Based on the analysis of all statements, the only true statement is the second one: "Large is the value of electron gaining enthalpy, easier is the formation of anion."