Assertion   :  The first ionization energy of Be is greater than that of BReason    :   2p orbital is lower in energy than 2s

The assertion and the reason given are not correct.

Assertion: The first ionization energy of Be is indeed greater than that of B. This is because Be has a completely filled 2s orbital, and it requires more energy to remove an electron from a completely filled orbital due to its stability.

Reason: However, the reason provided is incorrect. The 2p orbital is not lower in energy than the 2s orbital. In fact, the 2s orbital is lower in energy than the 2p orbital. This is based on the principles of quantum mechanics and the rules of electron configuration.

Therefore, while the assertion is correct, the reason provided is not the correct explanation for it.