Periodicity of elements and their properties

Element found in period four and group 5B, its atomic number is ........

• 21

• 22

• 23

• 24

The smallest atomic size of the following is ...........

Elements whose atomic numbers from 1 : 18 occupy ...... periods in the modern periodic table.

• 1

• 2

• 3

• 4

An element which is located in the third period and group 13, the number of neutrons in its nucleus equals 14, so its mass number equals .........

• 30

• 27

• 24

• 20

The chemical formula of Rubidium oxide is ............

Three elements (X, Y, Z) lie in the same period in the periodic table, if oxide of element (X) reacts with acids and bases, oxide of element (Y) reacts with bases only and oxide of element (Z) reacts with acids only. what is the correct order of atomic numbers of these elements?

• 16, 23

• 18, 23

• 18, 32

• 16, 16

Element (X) is from alkali metals, reacts with element (R) which belongs to group (15) to form a compound, whose chemical formula is ........

Element (X) is from alkali metals, reacts with element (Y) from group (17), a salt is produced, whose chemical formula is ..........

• More than

• Less than

• Equal to

• Double