Q: A wave has a wavelength of $$2.0\ \mathrm{m}$$ and a frequency of $$1.5 \times 10^8$\ \mathrm{Hz}. $$What is the speed of the wave?

$$3.0 \times 10^8$\ \mathrm{m/s}$$

Q: A 2.5 g Ping-Pong ball travels at $$15.6\ \mathrm{m/s}. $$What is its de Broglie wavelength?

$$1.7 \times 10$$^{-32}$$\ \mathrm{m}$$

Q: If the uncertainty in the position $$(\Delta x) of an $$electron is $$1\% of $$the radius of a hydrogen atom $$(5 \times 10$$^{-11}$$\ \mathrm{m})$$, what is the minimum uncertainty in its velocity $$(\Delta v)$$? (Electron mass $$= 9.11 \times 10$$^{-31}$$\ \mathrm{kg})$$

$$5 \times 10^4$\ \mathrm{m/s}$$

Question 1

Which of the following statements best describes the nature of electromagnetic radiation?

Accepted Answer

It is a form of radiant energy that has both electric and magnetic wave components.

Question 2

A wave has a wavelength of $$2.0\ \mathrm{m}$$ and a frequency of $$1.5 	imes 10^8$\ \mathrm{Hz}. $$What is the speed of the wave?

Accepted Answer

$$3.0 	imes 10^8$\ \mathrm{m/s}$$

Question 3

Which equation correctly relates the speed of light $$(c)$$, wavelength $$(\lambda)$$, and frequency $$(
u)$$?

Accepted Answer

$$c = \lambda 
u$$

Question 4

Planck’s solution to the blackbody radiation problem introduced which concept?

Accepted Answer

Energy is emitted or absorbed in discrete units called quanta.

Question 5

The energy of a photon is given by $$E = h 
u. If $$the frequency of a photon is doubled, what happens to its energy?

Accepted Answer

The energy is doubled.

Question 6

Which phenomenon provided evidence for the particle nature of light?

Accepted Answer

Photoelectric effect

Question 7

The Rydberg equation for the hydrogen atom is $$\frac{1}{\lambda} = R_H \left( \frac{1}{n_1$^2} - \frac{1}{n_2$^2} \right). $$What does $$n_2$$ represent?

Accepted Answer

The principal quantum number of the higher energy level

Question 8

According to the Bohr model, what is the energy of an electron in the $$nth $$orbit of hydrogen?

Accepted Answer

$$E_n = -hcR_H \frac{1}{n^2$}$$

Question 9

A hydrogen atom transitions from $$n=3 to$$ $$n=1. $$What is the correct formula to calculate the wavelength of the emitted photon?

Accepted Answer

$$\lambda = \frac{hc}{\Delta E}$$

Question 10

Louis de Broglie proposed that matter has wave-like properties. What is the de Broglie wavelength of a particle?

Accepted Answer

$$\lambda = \frac{h}{mv}$$

Question 11

A 2.5 g Ping-Pong ball travels at $$15.6\ \mathrm{m/s}. $$What is its de Broglie wavelength?

Accepted Answer

$$1.7 	imes 10$$^{-32}$$\ \mathrm{m}$$

Question 12

Heisenberg’s uncertainty principle can be mathematically expressed as:

Accepted Answer

$$\Delta x \Delta m v \geq \frac{h}{4\pi}$$

Question 13

Which of the following best explains why the de Broglie wavelength of a macroscopic object, such as a golf ball, is not observable?

Accepted Answer

Its mass is so large that the wavelength is extremely small.

Question 14

If the uncertainty in the position $$(\Delta x) of an $$electron is $$1\% of $$the radius of a hydrogen atom $$(5 	imes 10$$^{-11}$$\ \mathrm{m})$$, what is the minimum uncertainty in its velocity $$(\Delta v)$$? (Electron mass $$= 9.11 	imes 10$$^{-31}$$\ \mathrm{kg})$$

Accepted Answer

$$5 	imes 10^4$\ \mathrm{m/s}$$

Question 15

Which of the following is NOT a consequence of Heisenberg’s uncertainty principle?

Accepted Answer

The energy of a photon can be measured with absolute precision.

Electronic Structure of Atoms: Light, Quantization, and Atomic Models

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