Question

(a) As element X has mass number 40 and contains 21 neutrons in its atom. To which group of the periodic table does it belong?
(b) The element X forms a compound X2Y. Suggest an element that Y might be and give reasons for your choice.

Answer 1

Answer: The element X is Zirconium (Atomic mass. 40) It belongs to the 4th group in the modern periodic table.

Answer 2

Let us solve this problem and suggest the element

Explanation:

(a) Mass number of element X =40

Number of neutrons =21

The group to which it belongs : For this let us find protons .

Mass number =protons + neutrons

40=P-21

Protons =19

The configuration is 2,8,8,1

It is identified as Potassium and it belongs to group 1

b) The element X forms a compound X₂Y . The Y belongs to group 16 as its valency is -2 so, it can be O.

That is : K₂O

Potassium oxide