If $NaOH$ is added to an aqueous solution of zinc ions,a white precipitate appears and on adding excess $NaOH$,the precipitate dissolves. In this solution,zinc exists in the

Choose the correct order of the acidity for the following metal complexes:

Among the following,the $\pi$-acid ligand is

Given below are two statements: one is labelled as "Assertion $A$" and the other is labelled as "Reason $R$".
Assertion $A$: In the complexes $Ni(CO)_4$ and $Fe(CO)_5$,the metals have zero oxidation state.
Reason $R$: Low oxidation states are found when a complex has ligands capable of $\pi$-donor character in addition to the $\sigma$-bonding.
In the light of the above statements,choose the most appropriate answer from the options given below.

$AlF_3$ is soluble in $HF$ only in the presence of $KF$. This is due to the formation of:

Which of the following is non-ionizable?