In each of the following questions a Statement of Assertion (A ) is given followed by a corresponding statement of Reason (R ) Just below it . Of the statement mark the correct answer as
Assertion . The first ionization energy of Be is greater than that of B.
Reason . 2p- Orbitals is lower in energy than 2s- orbital.

Explanation

To solve the question, we need to analyze both the Assertion (A) and the Reason (R) provided.

### Step 1: Understand the Assertion
The assertion states that "The first ionization energy of Be is greater than that of B."

- **Ionization energy** is the energy required to remove an electron from an atom in its gaseous state.
- Beryllium (Be) has an electronic configuration of 1s² 2s², while boron (B) has a configuration of 1s² 2s² 2p¹.
- Since Be has a completely filled 2s subshell and B has one electron in the 2p subshell, it is generally expected that removing an electron from Be requires more energy due to its stable electron configuration.

### Step 2: Understand the Reason
The reason states that "2p-orbitals is lower in energy than 2s-orbital."

- This statement is incorrect. In fact, the 2s orbital is lower in energy than the 2p orbitals. The energy levels of orbitals increase in the order of 2s < 2p.
- This means that electrons in the 2s orbital are held more tightly by the nucleus compared to those in the 2p orbital.

### Step 3: Conclusion
- The assertion is **true**: The first ionization energy of Be is indeed greater than that of B.
- The reason is **false**: The 2p orbitals are not lower in energy than the 2s orbital.

### Final Answer
Based on the analysis:
- The correct answer is that the Assertion is true, but the Reason is false.

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