Question

The properties of _________ were predicted by Mendeleev before their isolation.

• A. Co and Ni
• B. I and Te
• C. Sc, Ga and Ge
• D. Cl, Ar and K

Answer 1

The correct option is C Sc, Ga and Ge

Mendeleev has the foresight to leave some gaps in the periodic table for 3 elements and these elements are discovered later and included in the table.

Those three elements are:
1) Eka-boron is presently known as scandium ($\text{Sc}$).
2) Eka-silicon is presently known as germanium ($\text{Ge}$).
3) Eka-aluminium is presently known as gallium($\text{Ga}$).

Hence, the correct option is $\text{C}$