Question 1

Which of the following statements best describes the main insight of Bohr’s model of the atom?

Accepted Answer

Electrons can only occupy specific energy levels, and transitions between these levels involve absorption or emission of quantized energy.

Question 2

According to Planck’s quantum theory, what is the relationship between the energy of a photon and the frequency of electromagnetic radiation?

Accepted Answer

$$E = h f$$

Question 3

Which experiment led to the discovery that atoms have a small, dense, positively charged nucleus?

Accepted Answer

Rutherford’s Gold Foil Experiment

Question 4

What problem did the ‘ultraviolet catastrophe’ reveal about classical physics?

Accepted Answer

It predicted infinite energy emission at short wavelengths, which was not observed experimentally.

Question 5

Which of the following best explains why the electromagnetic spectrum appears continuous to the human eye?

Accepted Answer

The energy differences between quantized levels are extremely small.

Question 6

If an electron in a hydrogen atom absorbs a photon and moves from $$n=2 to$$ $$n=4$$, what happens when it returns to $$n=2$$?

Accepted Answer

It emits a photon with energy equal to the difference between the two energy levels.

Question 7

Which equation gives the maximum number of electrons that can occupy a principal energy level $$n$$?

Accepted Answer

$$2n^2$$

Question 8

Which scientist first proposed that energy is quantized and introduced the constant $$h$$?

Accepted Answer

Max Planck

Question 9

A sodium street lamp emits yellow light with a frequency of $$5.09 	imes 10$$^{14}$$ Hz. Using Planck’s constant h = 6.626$$ 	imes $$10^{-34} J$$·s, what is the energy of one photon of this light?

Accepted Answer

$$3.37 	imes 10$$^{-19}$$ J

Question 10

Which observation led Einstein to propose the quantum theory of light?

Accepted Answer

The photoelectric effect, where light ejects electrons from a metal only above a certain frequency.

Question 11

Which of the following is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms are composed of electrons, protons, and neutrons.

Question 12

Which model of the atom was the first to include subatomic particles?

Accepted Answer

J.J. Thomson’s Plum Pudding Model

Question 13

A photon of ultraviolet light has a higher frequency than a photon of visible light. According to quantum theory, how does its energy compare?

Accepted Answer

The ultraviolet photon has more energy.

Question 14

Which of the following best describes the wave-particle duality of light?

Accepted Answer

Light exhibits both wave-like and particle-like properties depending on the experiment.

Question 15

Which real-world application relies on the quantization of energy levels in atoms?

Accepted Answer

The operation of fluorescent lamps, which emit light at specific wavelengths.

Question 16

If the energy of a photon is $$4.0 	imes 10$$^{-19}$$ J, what is its frequency? (Use h = 6.626$$ 	imes $$10^{-34} J$$·s)

Accepted Answer

$$6.04 	imes 10$$^{14}$$ Hz

Question 17

Which statement best explains why Bohr’s model was a significant improvement over Rutherford’s model?

Accepted Answer

Bohr’s model explained the stability of atoms and the discrete lines in atomic spectra.

Question 18

Which of the following is a direct consequence of the quantization of energy in atoms?

Accepted Answer

Atoms emit light at specific wavelengths, producing line spectra.

Question 19

Which historical model of the atom was disproven by the results of the gold foil experiment?

Accepted Answer

J.J. Thomson’s Plum Pudding Model

Atomic Theory and the Development of Quantum Theory

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