The highest oxidation state observed in first row transition metals is

Based on the quantum numbers, what will be the maximum number of element for sixth period of the periodic table?

Let's assume the $\mathrm{C}_1 \equiv \mathrm{C}_2$ bond is acetylene is along $Z$-axis. Find out the correct combination of atomic orbitals with non-zero overlapping.

Which of the following molecules is not paramagnetic in nature?