Assertion: Electron gain enthalpy value of the 3rd peirod p-block elements of the mordern periodic table are generally more negative than the 2nd period element of the same group.
Reason: Due to smaller atomic size of the 2nd peirod element, its electron density is high which eases the addition of electron.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If the 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 assertion is false but reason is true.

Answer

C

Explanation

Assertion: it is correct statement and this can be understood by taking the following example.
Negative electron gain enthalpy of `O` and `F` is less than `S` or `Ci` respectively.
Reason: It is incorrect statement: This is due to the fact that when an electron is added to `O` or `F` , the added electron goes to the smaller `n=2` energy level and experiences significant repulsion fromthe other electrons present in this level. In `S` or `Cl`, the electron goes to the larger `n=3` energy level and consequently occupies a larger region of space leading to much less electron-electron repulison.