What do scandium, gallium and germanium have in common? a) they all had the properties that mendeleev had predicted when he first published his periodic table. b) all three of these elements have the same number of protons and neutrons and the same properties. c) they were all discovered by mendeleev before he published the first periodic table. d) all three of these elements have the same atomic number and atomic mass and the same properties.

The three elements were actually unknown to science until the time Medeleev devised the periodic table. This made him to predict the atomic mass and other characteristics of these three elements, and technetium, with great accuracy. He called these predicted elements - ekaboron (Eb) (scandium), ekaaluminium (Ea) (Galium), ekamanganese (Em) (technetium), and ekasilicon (Es) (germanium).

A) They all had the properties that Mendeleev had predicted when he first published his periodic table.

10 years is the answer