Question

Statement 1: Electron gain enthalpy values of the $3^{rd}$ period $p$-block elements of the Modem periodic table are generally more negative than the $2^{nd}$ period element of the same group
Statement 2:Due to smaller atomic size of the $2^{nd}$ period element, its electron density is high which eases the addition of electron

• A. If both Statement $1$ and Statement $2$ are true and the statement $2$ is the correct explanation of the Statement $1$
• B. If both Statement $1$ and Statement $2$ are true but Statement $2$ is not the correct explanation of the Statement $1$
• C. If Statement $1$ is true but Statement $2$ is false
• D. If Statement $1$ is false but Statement $2$ is true

Answer 1

Answer: (C)

Statement $1$: 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 $Cl$ respectively
Statement $2$: 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 from the 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 repulsion