Chapter 7 Practice Test

Question 1

Which label is most appropriate for the horizontal scale of this diagram of the electromagnetic spectrum?

Answer 1

Increasing wavelength

Question 2

Blue light has a wavelength of about 475 nanometers. What is the period of light having this wavelength? (1 nanometer = 1 × 10^−9 meter)

Answer 2

1.58 × 10^−15 s

Question 3

Among other types of electromagnetic radiation, the sun radiates visible, infrared, and ultraviolet light. Which of these will take the longest to reach Earth through the near-vacuum of space?

Answer 3

All will take the same amount of time

Question 4

A solution that appears violet is used in an absorption experiment. The spectrum that results includes all wavelengths except those corresponding to yellow light. What can you conclude from this experiment?

Answer 4

The absence of yellow is perceived as violet.

Question 5

Where should the sample be placed in the following diagram in order to obtain the best emission spectrum?

Answer 5

A

Question 6

What did classical physics predict regarding an emission spectrum during incandescence?

Answer 6

Intensity increases with increasing frequency.

Question 7

In 1900, which of the following did Max Planck propose in order to solve the ultraviolet catastrophe?

Answer 7

He proposed that in a heated body, a discrete amount of energy is absorbed by the multiple oscillators

Question 8

Which of the following statements about Einstein’s explanation of the photoelectric effect is not correct?

Answer 8

Because light is packaged discretely, increasing the intensity of light will increase the number of photons hitting a metal and thus the likelihood that an electron will be ejected.

Question 9

A metal begins to emit electrons, as measured in an apparatus similar to the one Hertz used, when exposed to light at a wavelength of 342 nm (ultraviolet). What is the work function of this metal?

Answer 9

3.63 eV

Question 10

How much energy must an electron in a hydrogen atom absorb to move from the first (or lowest) energy level to the third energy level?

Answer 10

1.94 × 10^−18 J

Question 11

What frequency of light will be emitted from a lithium ion (Li 2+ ) when its electron drops from an energy level of n = 5 to an energy level of n = 2?

Answer 11

6.22 × 10^15 s−1

Question 12

For which of the following electrons will Δx, the minimum error in knowing its position, be the greatest? (An object’s momentum is equal to its mass multiplied by its velocity.)

Answer 12

an electron with a measured velocity of 1.8 × 10^5 m / s, plus or minus 2%

Question 13

The momentum of a proton is measured as 2.2 × 10^−21 kg • m / s. Suppose there is a 0.75% uncertainty in knowing the momentum. The minimum error in knowing this proton’s position is about how many times greater than the diameter of the proton?
The diameter of a proton is approximately 1 × 10^−15 m.

Answer 13

3000

Question 14

An atom of helium
has a de Broglie wavelength of
4.3 × 10^−12 meters.

What is its velocity?

Answer 14

2.3 × 10^4 m / s

Question 15

Which of these particles will have the shortest de Broglie wavelength?

Answer 15

A proton with a velocity of 9.0 × 10^5 m / s

Question 16

The x-, y- and z-coordinates of a point are (3, 4, 0). What is the value of r for this point, using spherical coordinates?

Answer 16

5

Question 17

Which of the following types of information cannot be determined from examining the solutions to the Schrödinger equation?

Answer 17

the shape of the path an electron takes around the nucleus

Question 18

How many angular nodes does a p orbital have?

Answer 18

1

Question 19

Which of the following orbitals has three spherical nodes, no planar nodes, and lacks directionality?

Answer 19

4s

Question 20

What information does Schrödinger’s equation combine?

Answer 20

kinetic energy, potential energy, and wave properties

Question 21

The Heisenberg uncertainty principle states that it is impossible to simultaneously know which two things about of an electron?

Answer 21

position, momentum

Question 22

What are the names for the three quantum numbers in the Schrödinger equation?

Answer 22

Principal, angular, magnetic.

Question 23

How many angular nodes do the d orbitals have?

Answer 23

2

Question 24

Electrons in the 2s and 2p orbitals have _______________ quantum numbers n and electrons in the 2s and 3s orbitals have _____________ quantum numbers n.

Answer 24

the same; different

Question 25

What frequency of light would cause the electron of a Li2+ ion to be ejected from the 1s orbital? The energy needed to remove this electron is 1.96 × 10^−17 J.

Answer 25

2.96 × 10^16 s−1