Question

Electronegativity of group 13 elements follow the order:
A: $B > Ca > Al > Tl > In$
B: $B > Tl > Ga > Al > In$
C: $B > Tl > In > Ga > Al$
D: $B > Al > Tl > In > Ga$

Answer 1

Hint: Electronegativity refers to the measurement of an ability of an atom to attract a shared pair of electrons. Electronegativity of an atom is influenced by its atomic number as well as the distance at which valence electrons of an atom are placed from the charged nucleus.

Complete step by step solution:
: Group 13 of the periodic table is known as Boron family which includes six elements i.e. boron (\[B\]), aluminum (\[Al\]), gallium (\[Ga\]), indium (\[In\]), thallium (\[Tl\]), and nihonium (\[Nh\]). We know that electronegativity depends upon two factors:
1) Size of the atom: Electronegativity increases with decrease in the size of an atom.
2) Magnitude of the nuclear charge: Electronegativity increases with increase in the magnitude of nuclear charge.
From top to bottom (i.e. down a group) in a periodic table, electronegativity decreases because atomic number usually increases down a group i.e. inert pair effect. The value of electronegativity (on a Pauling scale) of all elements in group 13 are:
$\begin{gathered}
  B:2.0 \\
  Al:1.5 \\
  Ga:1.6 \\
  In:1.7 \\
  Tl:1.8 \\
\end{gathered} $
Thus, it can be concluded that electronegativity of group 13 elements follow the order$B > Tl > In > Ga > Al$
Hence, the correct answer is Option C.

Note:
 The most electronegative elements in the periodic table are known as ‘FONCLBRISCH’. The most electronegative element lies on the top, while the least electronegative element lies on bottom. FONCLBRISCH stands for fluorine, oxygen, nitrogen, chlorine, bromine, iodine, sulphur, carbon, hydrogen.