General Science 7th Class Chapter 4 Structure of an Atom Solved Exercise

General Science

7th Class

Chapter 4

Structure of an Atom

Questions

4.1 Encircle the correct option.

1. An element with fifteen protons in its atomic nucleus has atomic number:

a. 5        b. 10        c. 15        d. 20

2. The central part of an atom is called:

a. electron        b. proton        c. neutron        d. nucleus

3. Letter K is used to express the ________ shell around the nucleus of an atom.

a. 1st        b. 2nd        c. 3rd        4. 4th

4. The total number of electrons which M shell can a accommodate:

a. 2        b. 8        c. 18        d. 32

5. The particle of an atom having negative charge on it:

a. electron        b. proton        c. neutron        d. nucleus

6. Atomic number of element present in period 2 and group 15 of the Periodic Table:

a. 4        b. 5        c. 6        d. 7

7. How many periods are there in the Periodic Table?

a. five        b. six        c. seven        d. eight

8. Formula showing maximum number of electrons in a shell:

a. n²        b. 2n²        c. 3n²        d. 4n²

9. The mass of an atom is almost due to the:

a. electrons        b. protons        c. neutrons        d. nucleus

10. The particles of an element having different mass numbers:

a. protons        b. neutrons        c. atoms        d. isotopes

4.2 Give short answers.

i. What is atom?

Ans.

An atom is the smallest particle of an element that takes part in a chemical reaction.

ii. Define element.

Ans.

Element is a substance which is made up of same type of atoms.

iii. What type of charge is present on neutron?

Ans.

Neutrons are neutral particles. They have no charge on them.

iv. What do you mean by atomic number?

Ans.

The number of protons present in an atom of an element is called atomic number of that element. It is donated as Z.

v. What is mass number?

Ans.

The total number of protons plus neutrons present in an atom of an element is called mass number of that element. It is donated as A.