Question

The $PbC{l_4}$ exists but $PbB{r_4}$ and $Pb{l_4}$ do not, because of:
(A) $B{r^ - }$ and ${I^ - }$ ions are bigger in size
(B) chlorine is a gas
(C) $B{r_2}$ and ${I_2}$ are more electronegative
(D) Inability of bromine and iodine to oxidise $P{b^{2 + }}$ and $P{b^{4 + }}$

Answer 1

To answer this question, recall the concept of trends in periodic table. The placement is based on modern periodic law. The modern periodic law states that the properties of the elements are a periodic function of their atomic numbers. As the properties of the elements are dependent upon the atomic number, we can say that these are dependent upon the electronic configuration of the elements.

Complete step by step solution:
$Pb$ is a big atom, so are $Br$ and $I$ . Because of their large sizes, it is difficult for the atoms to come close together to form the compound. Chlorine is a stronger oxidising agent which leads to $+ 2$ to $+ 4$ oxidation state but Br and I are weaker oxidising agents not oxidising lead from $+ 2$ to $+ 4$ oxidation state.
Therefore, the correct answer to this question is option A and D.

Additional information
The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is known as electronegativity. It is a dimensionless property because it is only a tendency. We measure electronegativity on several scales. The most commonly used scale was designed by Linus Pauling. According to this scale, fluorine is the most electronegative element with a value of 4.0 and cesium is the least electronegative element with a value of $0.7$ .
Electronegativity decreases in a group on going from top to bottom. Therefore, increasing electronegativity order is $I{\text{ }} < {\text{ }}Br{\text{ }} < {\text{ }}Cl{\text{ }} < {\text{ }}F.$

Note:
Let us summarize the trends of fundamental properties of an element: Atomic Radii and Ionic radii: The atomic radii and ionic radii of elements decrease while moving from left to right in a period. Ionization Enthalpy: Across a period in the periodic table, ionization energy generally increases. For the trend in a group, ionization enthalpy decreases from top to bottom. Electron gain enthalpy: Electron gain enthalpy becomes more negative as we move from left to right in a period. Electron gain enthalpy is negative when energy is released while accepting an electron. While it is positive when energy is supplied to an atom while adding an electron.