(C) The electronegativity of $Al$ is $1.61$ and that of $Tl$ is $1.62$. Thus,the electronegativity of $Tl$ is slightly greater than $Al$. Therefore,th

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Both Assertion $\&$ Reason are incorrect.

(C) The electronegativity of $Al$ is $1.61$ and that of $Tl$ is $1.62$. Thus,the electronegativity of $Tl$ is slightly greater than $Al$. Therefore,the Assertion is incorrect.In the Boron family,due to the poor shielding effect of $d$ and $f$ orbitals (lanthanoid contraction),the atomic size does not increase regularly down the group. The size of $Ga$ is almost equal to $Al$. Therefore,the Reason is also incorrect.

Class 11 Chemistry Classification of Elements and Periodicity in Properties Electronegativity

Medium

Assertion $:$ Electronegativity of $Al$ is greater than $Tl$.
Reason $:$ In a Boron family,down the group regularly size increases.

A
Assertion and Reason both are correct but Reason is not correct explanation of Assertion.
B
Assertion is correct but Reason is incorrect.
C
Both Assertion $\&$ Reason are incorrect.
D
Assertion and Reason both are correct but Reason is correct explanation of Assertion.