1. The atom – Worksheet – By Aditya Abeysinghe 1
1. A neutral atom consists of
i. Only Protons
ii. Only Neutrons and Protons
iii. Only Neutrons
iv. Only Neutrons, Protons and Electrons
v. Only Neutrons and Electrons
2. Two neutral isotopes of an element differs by their,
i. Atomic number
ii. Number of electrons
iii. Number of positrons
iv. Number of neutrons
v. Chemical reactivity
3. Which of the following is an accurate conclusion from
Rutherford’s alpha scattering experiment
i. Neutrons are always embedded inside the nucleus
ii. Neutrons and Electrons always revolve around the nucleus
iii. Most of the volume inside an atom attributes to the space
occupied by its nucleus
iv. Electrons revolve around the nucleus in energy levels
v. The mass of the atom is concentrated to its center.

2. The atom – Worksheet – By Aditya Abeysinghe 2
4. Which of the following is inaccurate about canal/ anode rays?
i. Charge to mass ratio depends on the gas used
ii. Are positively charged
iii. Maximum e/m ratio can be obtained by introducing H2 to
the cathode ray tube
iv. e/m ratio for different canal rays are the same
v. Canal rays are produced consequently as cathode rays are
generated
5. When alpha particles are allowed to penetrate a gold foil, most of
these particles show a deviation from the foil. This is due to,
i. Alpha particles colliding with the nucleus
ii. The attraction from the nucleus
iii. The collision with nucleus
iv. The attraction created by the electron cloud
v. The static electric repulsion created by the nucleus
6. Why are electrons in an atom considered to be in a lost energy
state as described by the Thomson’s experiments?
i. Electrons collide with each other
ii. Electrons move with acceleration/ are accelerating
iii. Electrons are moving
iv. Electrons stay in specific energy levels
v. Electrons are attracted towards the nucleus

3. The atom – Worksheet – By Aditya Abeysinghe 3
7. An atom can be considered neutral,
i. When there are no charged particles
ii. When the number of positive charges are equal to the
number of negative charges
iii. Since neutrons, neutral particles, are always present in an
atom
iv. Due to (i) and (iii)
v. Due to all of the above
For the following questions (8-10) use the criteria below when selecting
answers.
Criteria First Sentence Second Sentence
( 1 ) True True and explains the first sentence
( 2 ) True True but does not explain the first
sentence
( 3 ) True False
( 4 ) False True
( 5 ) False False

4. The atom – Worksheet – By Aditya Abeysinghe 4
8 Cathode rays deviate when
faced with a magnetic field
Since cathode rays are
composed of positive
particles
9 The transparence capability
of β radiation is extremely
high
β radiation are electrons
travelling at high speeds
10 β radiation can ionize air
particles
β particles are electrons
travelling at high speeds

5. The atom – Worksheet – By Aditya Abeysinghe 5
Answers-
1. 4
2. 4
3. 5
4. 4
5. 5
6. 5
7. 2
8. 3
9. 4
10. 1