The basic difference in approach between Mendeleev's periodic law and modern periodic law is the change on the basis of classification of elements from

Which of the following pairs shows diagonal relationship?

Among the following, the pair of elements having same electronegativity values are

I. H and $\mathrm{P} \quad$ II. Be and Al III. N and $\mathrm{Cl} \quad$ IV. C and P

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