Question

Direction for Assertion - Reason type questions (A) If both Assertion and Reason are true and reason is the correct explanation of assertion. (B) If both Assertion and Reason are true but Reason is not the correct explanation of assertion. (C) If Assertion is true but Reason is false (D) If both assertion and reason are false A: The ionization energy of isolated phosphorous is very large \(\mathrm{R}\) : The ionization energy of phosphorous in lattice is very small (A) a (B) \(b\) (C) \(\mathrm{c}\) (D) \(\mathrm{d}\)

Short answer

The correct answer is (C). The ionization energy of isolated phosphorous is very large, while the ionization energy of phosphorous in lattice is not necessarily 'very small'.

Step-by-step solution

Understand the Terms

Firstly, it is important to comprehend the terms being used. 'Ionization energy' is the energy required to remove an electron from an atom or ion. 'Isolated' phosphorous refers to an individual atom of phosphorous, without any connection to other atoms. 'In lattice' refers to phosphorous as part of a crystal structure where it is bonded with other atoms.

Assess the Assertion

The assertion is: 'The ionization energy of isolated phosphorous is very large.' The isolation energy is typically large for phosphorous. This is because when an atom is isolated, removing an electron would significantly disrupt its stability, requiring a large energy input. So this statement is true.

Assess the Reason

The reason is: 'The ionization energy of phosphorous in lattice is very small.' When phosphorous is in a lattice, it is bonded to other atoms and has lower energy than when it is isolated, making it easier to ionize. However, the statement is not entirely accurate. Even though the energy is lower compared to the isolated state, it might not be right to say that it is 'very small'. So this statement is not necessarily always true.

Analyse the Relationship and Choose the Correct Answer

Since the Assertion is true and the Reason is not entirely true, the best answer would be (C), Assertion is true but Reason is false. While the ionization energy for phosphorous in lattice is smaller than isolated phosphorous, it's not accurate to definitively define it as 'very small'. As these statements are directly linked, the Reason does not correctly explain the Assertion. Thus, the correct answer is (C).