In Mendeleev's periodic table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later ?

Options

A. It helped in correcting the atomic masses of some of the elements.
B. HE predicted the properties of some undiscovered elements and left gaps for them.
C. He framed the periodic table with vertical and horizontal columns and gave shape to it.
D. He gave separate places to isotopes in his periodic table.

Answer

D

Explanation

Mendeleev could not give separate places to isotopes which had different atomic weights in the periodic table.