Question 1

Which statement best describes the quantisation of energy in atoms?

Accepted Answer

Electrons in an atom can only occupy specific energy levels, not values in between.

Question 2

What is the primary difference between the ground state and the excited state of an atom?

Accepted Answer

The excited state is when electrons occupy higher energy levels than the ground state.

Question 3

An electron in a hydrogen atom absorbs a photon and jumps from $$n=2 to$$ $$n=4. $$Which statement is correct?

Accepted Answer

The electron must absorb energy exactly equal to the difference between $$n=2$$ and $$n=4.$$

Question 4

Which equation correctly relates the energy of a photon to its frequency?

Accepted Answer

$$E = h 
u$$

Question 5

Why do different elements have unique emission spectra?

Accepted Answer

Each element has a unique set of energy levels for its electrons.

Question 6

A sample of hydrogen is exposed to a continuous spectrum of visible light. Which wavelengths are absorbed?

Accepted Answer

Only wavelengths that correspond to the energy needed for electrons to jump to higher energy levels.

Question 7

Which process results in the formation of absorption lines in a spectrum?

Accepted Answer

Electrons absorb photons and jump to higher energy levels.

Question 8

When an electron returns from an excited state to the ground state, what is emitted?

Accepted Answer

A photon of electromagnetic radiation

Question 9

Which of the following best explains why emission spectra consist of discrete lines?

Accepted Answer

Electrons emit photons with energies equal to the differences between quantised energy levels.

Question 10

A scientist observes the emission spectrum of a hot gas. What does the pattern of lines indicate?

Accepted Answer

The unique energy level differences of the atoms in the gas

Question 11

Which of the following is true about the absorption spectrum of hydrogen?

Accepted Answer

It contains dark lines at wavelengths where electrons absorb energy to jump to higher levels.

Question 12

If an electron in an atom moves from $$n=5 to$$ $$n=2$$, what happens?

Accepted Answer

The atom emits a photon with energy equal to the difference between $$n=5$$ and $$n=2.$$

Question 13

Which formula relates the wavelength $$\lambda of $$light to its frequency $$
u$$ and the speed of light $$c$$?

Accepted Answer

$$c = \lambda 
u$$

Question 14

Why can't electrons 'linger' between energy levels in an atom?

Accepted Answer

Because electrons can only exist in quantised energy states.

Question 15

Which of the following best describes the process that produces emission lines in a spectrum?

Accepted Answer

Electrons release energy as they fall to lower energy levels.

Question 16

A cold gas is placed in front of a source emitting a continuous spectrum of light. What will be observed?

Accepted Answer

An absorption line spectrum

Question 17

Which of the following is NOT a characteristic of electromagnetic radiation?

Accepted Answer

It can be described by its mass.

Question 18

In a real-world application, how do astronomers use emission and absorption spectra?

Accepted Answer

To identify the elements present in distant stars.

Question 19

Which statement about the excited state of an atom is correct?

Accepted Answer

The excited state is unstable and electrons quickly return to the ground state.

Question 20

If an electron absorbs energy and jumps from $$n=1 to$$ $$n=3$$, what is the minimum energy required?

Accepted Answer

The energy difference between $$n=1$$ and $$n=3.$$

Quantisation of Energy: Energy Levels, Spectra, and Electromagnetic Radiation

Study Guide - Practice Questions