Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionization enthalpy?

Which of the following statements is incorrect?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In $T \ell I_{3}$,isomorphous to $CsI_{3}$,the metal is present in $+1$ oxidation state.
Reason $R$: $T \ell$ metal has fourteen $f$ electrons in the electronic configuration.
In the light of the above statements,choose the most appropriate answer from the options given below:

The aqueous solution of which of the following ion is colourless?

Which of the following is paramagnetic?

Which of the following metals exists in a liquid state during the summer season?