Question 1

Which of the following conclusions was drawn from J.J. Thomson’s cathode ray tube experiment?

Accepted Answer

Electrons are negatively charged particles with a low mass.

Question 2

In Millikan’s oil drop experiment, what was the significance of the observation that the charge on each oil drop was always a whole-number multiple of a fundamental value?

Accepted Answer

It demonstrated that charge is quantized and electrons have a fixed charge.

Question 3

Which equation correctly represents the calculation of the mass of an electron using the charge-to-mass ratio and the elementary charge?

Accepted Answer

$$m = \frac{e}{\left(\frac{e}{m}\right)}$$

Question 4

What did the deflection of cathode rays toward the positive plate in an electric field demonstrate?

Accepted Answer

Cathode rays are composed of negatively charged particles.

Question 5

Which of the following statements best describes the plum pudding model of the atom proposed by J.J. Thomson?

Accepted Answer

Electrons are embedded in a sphere of positive charge.

Question 6

In Rutherford’s gold foil experiment, why was the observation that some alpha particles were deflected at large angles significant?

Accepted Answer

It suggested the existence of a small, dense, positively charged nucleus.

Question 7

Which of the following is NOT a postulate of Rutherford’s nuclear theory of the atom?

Accepted Answer

Electrons are embedded within a positively charged sphere.

Question 8

A scientist observes that when a magnetic field is applied perpendicular to the path of cathode rays, the rays are deflected. What does this observation support?

Accepted Answer

Cathode rays have mass and charge.

Question 9

If the charge of an electron is $$1.602 	imes 10$$^{-19}$$ C and the charge-to-mass ratio is 1.759$$ 	imes $$10^{11} C/kg$$, what is the mass of an electron?

Accepted Answer

$$9.109 	imes 10$$^{-31}$$ kg

Question 10

Which real-world application relies on the principles discovered in the cathode ray tube experiment?

Accepted Answer

The operation of modern television and computer screens (CRT displays)

Question 11

Which experiment provided the first direct evidence for the existence of subatomic particles?

Accepted Answer

Thomson’s cathode ray tube experiment

Question 12

Why did Rutherford conclude that most of the atom is empty space?

Accepted Answer

Most alpha particles passed straight through the gold foil without deflection.

Question 13

Which of the following best explains why atoms are electrically neutral according to Rutherford’s nuclear model?

Accepted Answer

The number of protons equals the number of electrons.

Question 14

A student claims that Millikan’s oil drop experiment measured the mass of the electron directly. Is this correct?

Accepted Answer

No, because it only measured the charge of the electron.

Question 15

Which observation from the gold foil experiment was inconsistent with the plum pudding model?

Accepted Answer

Some alpha particles were deflected at large angles.

Question 16

Which of the following is a correct statement about the structure of the atom based on Rutherford’s findings?

Accepted Answer

The nucleus contains most of the atom’s mass.

Discovery of the Electron and Structure of the Atom: Key Experiments and Models

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