Classification ...

Mendeleev used a Sanskrit numeral before the names of the predicted elements. What was the term used for it?

The electronic configuration of sulphur is :

Which periods were not divided into two series in the Mendeleev's periodic table?

Reactivity of elements ........ down the group.

An atom has electronic configuration $$2,\,8,\,7$$. To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses)

Reactivity of elements .............. across a period.

The smallest period in the modern periodic table contains ............ elements.

On moving across a period, the tendency to gain electrons:

The sum of the number of elements of fifth and sixth period is :

In the Modern periodic table, calcium (atomic number $$20$$) is surrounded by elements with atomic numbers $$12,\,19,\,21,\,38$$. Which of these have physical and chemical properties resembling calcium?