The atom – Worksheet – By Aditya Abeysinghe 1

1. A neutral atom consists ofi. Only Protons

ii. Only Neutrons and Protonsiii. Only Neutronsiv. Only Neutrons, Protons and Electronsv. Only Neutrons and Electrons

2. Two neutral isotopes of an element differs by their,i. Atomic number

ii. Number of electronsiii. Number of positronsiv. Number of neutronsv. Chemical reactivity

3. Which of the following is an accurate conclusion fromRutherford’s alpha scattering experiment

i. Neutrons are always embedded inside the nucleusii. Neutrons and Electrons always revolve around the nucleusiii. Most of the volume inside an atom attributes to the space

occupied by its nucleusiv. Electrons revolve around the nucleus in energy levelsv. The mass of the atom is concentrated to its center.

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 chargediii. Maximum e/m ratio can be obtained by introducing H2 to

the cathode ray tubeiv. e/m ratio for different canal rays are the samev. Canal rays are produced consequently as cathode rays are

generated

5. When alpha particles are allowed to penetrate a gold foil, most ofthese particles show a deviation from the foil. This is due to,

i. Alpha particles colliding with the nucleusii. The attraction from the nucleusiii. The collision with nucleusiv. The attraction created by the electron cloudv. The static electric repulsion created by the nucleus

6. Why are electrons in an atom considered to be in a lost energystate as described by the Thomson’s experiments?

i. Electrons collide with each otherii. Electrons move with acceleration/ are acceleratingiii. Electrons are movingiv. Electrons stay in specific energy levelsv. Electrons are attracted towards the nucleus

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 thenumber of negative charges

iii. Since neutrons, neutral particles, are always present in anatom

iv. Due to (i) and (iii)v. Due to all of the above

For the following questions (8-10) use the criteria below when selectinganswers.

Criteria First Sentence Second Sentence

( 1 ) True True and explains the first sentence

( 2 ) True True but does not explain the firstsentence

( 3 ) True False

( 4 ) False True

( 5 ) False False

The atom – Worksheet – By Aditya Abeysinghe 4

8 Cathode rays deviate whenfaced with a magnetic field

Since cathode rays arecomposed of positiveparticles

9 The transparence capabilityof β radiation is extremelyhigh

β radiation are electronstravelling at high speeds

10 β radiation can ionize airparticles

β particles are electronstravelling at high speeds

The atom – Worksheet – By Aditya Abeysinghe 5

Answers-

1. 42. 43. 54. 45. 56. 57. 28. 39. 410. 1