Question 1

Which of the following best explains why modern blimps are filled with helium instead of hydrogen?

Accepted Answer

Helium is an inert gas with a stable electron configuration, making it nonreactive and safe.

Question 2

Which statement about the Bohr model of the atom is correct?

Accepted Answer

Electrons occupy quantized orbits with fixed energies, and cannot exist between orbits.

Question 3

Arrange the following types of electromagnetic radiation in order of increasing energy per photon: microwaves, visible light, X-rays.

Accepted Answer

Microwaves, visible light, X-rays

Question 4

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

Accepted Answer

$$c = \lambda 
u$$

Question 5

A red shirt appears red because:

Accepted Answer

It reflects red light and absorbs all other colors.

Question 6

Which of the following best describes the quantum-mechanical model of the atom?

Accepted Answer

Electrons are found in orbitals, which are probability maps showing where the electron is likely to be found.

Question 7

Which of the following electron configurations represents a ground-state carbon atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 8

Which principle states that no more than two electrons can occupy the same orbital, and they must have opposite spins?

Accepted Answer

Pauli exclusion principle

Question 9

Why are the noble gases chemically inert?

Accepted Answer

They have a full outer shell of electrons, making them stable and low in energy.

Question 10

Which of the following elements is most likely to form a $$2+$$ ion?

Accepted Answer

Magnesium (Mg)

Question 11

Which periodic trend is correctly described?

Accepted Answer

Ionization energy increases as you move to the right across a period.

Question 12

Which block of the periodic table contains the transition metals?

Accepted Answer

d block

Question 13

What is the electron configuration for sodium (Na, atomic number 11) using noble gas core notation?

Accepted Answer

$$[Ne]\ 3s^1$

Question 14

Which of the following statements about electromagnetic radiation is FALSE?

Accepted Answer

Microwaves have shorter wavelengths than ultraviolet light.

Question 15

A photon of which color of visible light carries the most energy?

Accepted Answer

Violet

Question 16

Which of the following best describes Hund’s rule?

Accepted Answer

Electrons occupy orbitals of equal energy singly before pairing.

Question 17

Which of the following is a real-world application of ionizing radiation discussed in the materials?

Accepted Answer

Destroying cancer cells in radiation therapy

Question 18

Which element has 6 valence electrons and is in the fourth period?

Accepted Answer

Selenium (Se)

Question 19

Which of the following statements about electron configurations and the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties due to similar valence electron configurations.

Question 20

Which of the following is the correct order of filling for the first several atomic orbitals?

Accepted Answer

$$1s, 2s, 2p, 3s, 3p, 4s, 3d$$

Electrons in Atoms and the Periodic Table: Models, Configurations, and Periodic Trends

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