Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: In $Tl{I}_3$, isomorphous to $Cs{I}_3$, the metal is present in $+1$ oxidation
state.

Reason R: $Tl$ metals has fourteen $f$ electrons in its electronic configuration.

In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both A and R are correct and R is the correct explanation of A
• B. A is not correct but R is correct
• C. Both A and R are correct and R is not the correct explanation of A
• D. A is correct but R is not correct

Answer 1

The correct option is C Both A and R are correct and R is not the correct explanation of A

The electronic configuration of thalium is $\left[Xe\right]4f^{14}5d^{10}6s^{2}6p^1$.
The oxidation state of Tl is +1 which gives fully filled stable electronic configuration.

$Tl{I}_3$ is $T{l}^{+}{I}_3^{-}$
$Cs{I}_3$ is $C{s}^{+}{I}_3^{-}$

Both have same crystalline structure. Hence, they are isomorphous.
Thus, (c) is the most appropriate answer.