Question 2 - CBSE Class 10 Sample Paper for 2022 Boards [Term 2] - Science Solution - Solutions to CBSE Sample Paper - Science Class 10

The diagram below shows part of the periodic table.

a. Which elements would react together to form covalent compounds?

b. Between the two elements W and Z, which will have a bigger atomic radius? Why?

Answer

a. Y and Z

b. W is bigger

Reason: Down the group number of shells increases

Explanation

In this question, there are 3 elements ,W,Y and Z

Element W

It lies in second group (Column) of Periodic Table

it means there are 2 Valence Electronic in outermost shell

It needs to loose 2 electrons to form compound

This is not possible in Covalent bonds where atoms share electrons (and not loose them)

Element Y

It lies in Sixth group (Column) of Periodic Table

it means there are 6 Valence Electronic in outermost shell

It needs to gain 2 electrons to form compound

Element Z

It lies in seventh group ( Column) of Periodic Table

it means there are 7 Valence Electronic in outermost shell

It needs to gain 1 electrons to become stable

Since Element Y and Z both want to gain electrons, they can share electrons with other to form covalent bonds

So, one Y atom shares its 2 electrons with 2 atoms of Z to achieve inert gas configuration

Since, there is sharing of electron, it is a covalent bond

Between the two elements W and Z, which will have a bigger atomic radius? Why?

Explanation

• As we go down the periodic table, the number of shells increase
• Due to increase in number of shells, atomic radius also increases

Now, Comparing W and Z

Since, W has more number of shells, it will have more atomic radius