Question

What is even odd series in periodic table in 4 ,5 and 6 periods.

(In byju study material it is given that Mendeleev failed to explain it in his table)

Answer 1

Its true
by Mendeleev’s periodic table, the hydrogen-series is taken as the 1st series, and the elements occupying places on even serial numbers in the series are said to be the elements of even series whereas the elements placed on odd serial numbers in the series are called elements of the odd series...