CBSE Class 9 Science Worksheet
Unit 1-Matter - Its Nature & Behaviour - Structure Of Atom
1.
Who discovered presence of neutrons in the nucleus of an atom?
A)
J. Chadwick
B)
James Rutherford
C)
Neils Bohr
D)
J J Thomson
2.
Choose the correct option: Elements with valency 1 are ________.
A)
Always metals
B)
Always non metals
C)
Metals and non metals
D)
Always semi conductors
3.
Choose the correct option: Rutherford’s alpha-particle scattering experiment was responsible for the discovery of __________.
A)
Electrons
B)
Protons
C)
Neutrons
D)
Atomic nucleus
4.
What were the drawbacks of Rutherford’s model of an atom?
5.
State True/False: Maximum number of the electrons that can be accommodated in L shell(orbit) of an atom are 8.
A)
1
B)
0
6.
Two isotopes of Copper, 63Cu has a mass of 62.930 u and 65Cu has a mass of 64.928 u. The percent abundance of 63Cu is 69.09%. Calculate the atomic mass of copper.
7.
Fill in the Blanks: The electronic configuration of sulphur is __________.
8.
Fill in the Blanks: ___________ rays are used in television picture tube.
9.
Fill in the Blanks: Discovery of protons is credited to __________.
10.
State True/False: The mass of an electron is about 1/2000 times that of proton.
A)
1
B)
0
11.
Choose the correct option: The heaviest particle among all the four given particles is _________ .
A)
Electron
B)
Proton
C)
Neutron
D)
Meson
12.
Which of the following element has the tendency to lose the electrons?
A)
Chlorine
B)
Flourine
C)
Helium
D)
Potassium
13.
State True/False: J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
A)
1
B)
0
14.
The ratio of the radii of hydrogen atom and its nucleus is ~ 105. Assuming the atom and the nucleus to be spherical, what will be the ratio of their sizes?
15.
The ion of an element has 2 positive charges. Mass number of the atom is 9 and the number of neutrons is 5. What is the number of electrons in the ion?
A)
2
B)
4
C)
5
D)
9
16.
State True/False: The electrons do not radiate energy while revolving in discrete orbits.
A)
1
B)
0
17.
Fill in the Blanks: Isotopes are atoms of the same element, which have different ___________.
18.
Which sub atomic particle which has no charge?
A)
Electron
B)
Neuton
C)
Proton
D)
None of these
19.
Electronic configuration and chemical properties are dependent on one another in atom
A)
True
B)
False
20.
Choose the correct option: Valency of Helium is _______
A)
0
B)
1
C)
2
D)
4
CBSE Class 9 Science Worksheet
Unit 1-Matter - Its Nature & Behaviour - Structure Of Atom
Answers
1.
Option A
2.
Option C
3.
Option D
4.
As per Rutherford, electrons revolve around the nucleus in fixed paths called orbits. An electron revolving around the nucleus should emit electromagnetic radiation as per Maxwell's theory.This radiation would carry energy from the motion of the electron results in shrinking of orbits and as a result, electrons will finally fall into the nucleus which causes the atoms to be very highly unstable and non-existent.
5.
Option A
6.
63.55u
7.
2,8,6
8.
Cathode
9.
E Goldstein
10.
Option A
11.
Option C
12.
Option D
13.
Option B
14.
1015
15.
Option A
16.
Option A
17.
Mass Numbers
18.
Option B
19.
Option A
Solution:
Yes dependent on one another.
20.
Option A
