In a vacuum, all electromagnetic radiation travels at the same speed, about 3.00 × 10^8 m/s.
Correct Answer
True
True. Radio waves, visible light and gamma rays all travel at the speed of light in a vacuum. They differ in wavelength and frequency, but their product is always the same constant, c.
Category: Electromagnetic Radiation
Question 2
Red light has a shorter wavelength than blue light.
Correct Answer
False
False. Red light has a longer wavelength than blue light, roughly 700 nm compared with about 450 nm. Its photons therefore have lower frequency and lower energy than blue photons.
Category: Electromagnetic Radiation
Question 3
Max Planck proposed that energy is emitted or absorbed only in discrete amounts called quanta.
Correct Answer
True
True. To explain blackbody radiation, Planck proposed that energy changes come in small, fixed packets, or quanta, each proportional to the frequency of the radiation. This idea launched quantum theory.
Category: Quantum Theory
Question 4
The line spectrum of a heated gas of hydrogen atoms is a continuous band containing every visible wavelength.
Correct Answer
False
False. Excited hydrogen atoms emit light only at certain specific wavelengths, which appear as separate bright lines. This pattern shows that the electron can have only certain energies.
Category: Bohr Model
Question 5
In the Bohr model, an electron absorbs energy when it moves from a lower energy level to a higher one.
Correct Answer
True
True. Moving to a level farther from the nucleus raises the electron's energy, so the atom must absorb exactly the energy difference between the two levels. Dropping back down releases that energy as a photon.
Category: Bohr Model
Question 6
According to de Broglie, a moving electron has particle properties but no wave properties.
Correct Answer
False
False. De Broglie proposed that moving matter, including electrons, has wave properties, with a wavelength equal to Planck's constant divided by momentum. Electron diffraction experiments later confirmed this wave behavior.
Category: Quantum Theory
Question 7
The Heisenberg uncertainty principle states that the exact position and the exact momentum of an electron cannot both be known at the same time.
Correct Answer
True
True. The more precisely one of these quantities is known, the less precisely the other can be known. For this reason, quantum mechanics describes electrons in terms of probabilities rather than exact paths.
Category: Quantum Theory
Question 8
Electrons in a ground-state atom fill higher-energy subshells before lower-energy ones.
Correct Answer
False
False. In the ground state, electrons occupy the lowest-energy subshells first and move to higher ones only as the lower ones fill. This building-up pattern is called the aufbau principle.
Category: Electron Configurations
Question 9
An s orbital has a spherical shape.
Correct Answer
True
True. Every s orbital, whatever its value of n, is spherically symmetric around the nucleus. Larger s orbitals, such as 2s and 3s, are bigger spheres that contain spherical nodes.
Category: Quantum Numbers and Orbitals
Question 10
The magnetic quantum number determines the size and main energy of an orbital.
Correct Answer
False
False. Size and main energy level are set by the principal quantum number, n. The magnetic quantum number, ml, specifies the orientation of an orbital in space.
Category: Quantum Numbers and Orbitals
Question 11
A single orbital can hold at most two electrons, and those two electrons must have opposite spins.
Correct Answer
True
True. Two electrons in one orbital share the same n, l and ml, so they must differ in ms, one +1/2 and one -1/2. A third electron would have to repeat a set of quantum numbers, which is not allowed.
Category: Quantum Numbers and Orbitals
Question 12
The three p orbitals in a subshell all point along the same axis.
Correct Answer
False
False. The three p orbitals are oriented at right angles to one another, along the x, y and z axes. Each has a dumbbell shape with two lobes on opposite sides of the nucleus.
Category: Quantum Numbers and Orbitals
Question 13
Elements in the same group of the periodic table have similar valence electron configurations.
Correct Answer
True
True. For example, every group 1 element has a single electron in its outermost s subshell. These shared outer configurations explain why elements in a group behave similarly in reactions.
Category: Electron Configurations
Question 14
Transition metals are the elements in which an f subshell is being filled.
Correct Answer
False
False. Transition metals are the d-block elements, in which a d subshell is being filled. Elements filling an f subshell are the inner transition metals shown in the two rows below the main table.
Category: Electron Configurations
Question 15
A cation is smaller than the neutral atom from which it forms.
Correct Answer
True
True. Losing electrons often empties the outermost shell and reduces electron repulsion, so the remaining electrons are pulled closer to the nucleus. For a given element, the greater the positive charge, the smaller the cation.
Category: Periodic Trends
Question 16
Fluorine has a more negative electron affinity than chlorine.
Correct Answer
False
False. Chlorine's electron affinity is more negative than fluorine's, even though fluorine is above it in group 17. Fluorine's small n = 2 shell is crowded, so an added electron feels strong repulsion from the electrons already there.
Category: Periodic Trends
Question 17
First ionization energy generally decreases going down a group of the periodic table.
Correct Answer
True
True. Moving down a group, the outermost electron is in a higher shell, farther from the nucleus and better shielded by inner electrons, so it is easier to remove. Cesium, for example, loses its outer electron far more easily than lithium.
Category: Periodic Trends
Question 18
Noble gases readily accept an extra electron because their outer shells are completely filled.
Correct Answer
False
False. Because a noble gas's shell is already full, an added electron would have to enter a new, higher shell, which is energetically unfavorable. Noble gases therefore do not readily form negative ions.
Category: Periodic Trends
Question 19
The ground-state electron configuration of copper is [Ar] 4s1 3d10.
Correct Answer
True
True. Copper is an exception to the simple filling order: one 4s electron moves into the 3d subshell, which then becomes completely filled. A filled d subshell is especially stable, so [Ar] 4s1 3d10 is observed instead of [Ar] 4s2 3d9.
Category: Electron Configurations
Question 20
All types of electromagnetic radiation can be seen by the human eye.
Correct Answer
False
False. The eye detects only the narrow visible region, from roughly 400 nm to 700 nm. Radio waves, microwaves, infrared, ultraviolet, X-rays and gamma rays are all invisible to us.
Category: Electromagnetic Radiation