Daily Practice Problems
Class 9 Science
Structure of The Atom
daily practice problem

Question 1.

What are canal rays?


Question 2.

A sub-atomic particle had a charge, equal in magnitude but opposite in sign to that of the electron is _________.


Question 3.

If an atom contains one electron and one proton, will it carry any charge or not?


Question 4.

Who proposed the model of an atom to be similar to that of a Christmas pudding?

a. Ernest Rutherford

b. J.J. Thomson

c. Dalton

d. Neils Bohr


Question 5.

What was Thomson’s model of atom?


Question 6.

In the experiment designed by Rutherford the what were the α-particles?


Question 7.

Which of the following was not an observation of α-particle scattering experiment?

a. Most of the fast moving α-particles passed straight through the gold foil.

b. Some of the α-particles were deflected by the foil by small angles.

c. One out of every 12000 particles appeared to rebound.

d. While revolving in discrete orbits the electrons do not radiate energy.


Question 8.

What were the conclusions of Rutherford’s model of atom?


Question 9.

What was Rutherford’s model of atom?


Question 10.

Who discovered neutrons?

a. John Dalton

b. J. Chadwick

c. Ernest Rutherford

d. J.J. Thomson


Question 11.

Which of the following statement regarding neutron is incorrect?

a. They are positively charged.

b. They have no charge.

c. Their mass is equal to that of proton.

d. They are present in the nucleus of atom.


Question 12.

How do we get the mass of an atom?


Question 13.

The orbits or shells in an atom are called _______.


Question 14.

Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?


Question 15.

How do you calculate the maximum number of electrons present in a shell?


Question 16.

What is the maximum number of electrons in the third orbit?


Question 17.

The maximum number of electrons that can be accommodated in the outermost orbit is ______.


Question 18.

How will you calculate the valency of fluorine?


Question 19.

What is valency?


Question 20.

What are isotopes and what are their uses?