Question 1

Which of the following best explains why modern blimps use helium instead of hydrogen for buoyancy?

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 travel in circular orbits at specific, quantized distances from the nucleus.

Question 3

A red shirt appears red because:

Accepted Answer

It reflects red light and absorbs all other colors.

Question 4

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

Accepted Answer

Microwaves \u003c Visible light \u003c X-rays

Question 5

Which of the following best describes the relationship between wavelength ($$\lambda) $$and frequency ($$
u) of $$light?

Accepted Answer

They are inversely proportional.

Question 6

Which region of the electromagnetic spectrum has the shortest wavelength and the highest energy?

Accepted Answer

Gamma rays

Question 7

A hydrogen atom emits a photon with a wavelength of 486 nm. According to the Bohr model, this corresponds to an electron transition from:

Accepted Answer

$$n = 4$$ \rightarrow $$n = 2$$

Question 8

Which of the following statements about quantum-mechanical orbitals is TRUE?

Accepted Answer

Orbitals are probability maps showing where an electron is likely to be found.

Question 9

What is the electron configuration for a ground-state carbon atom?

Accepted Answer

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

Question 10

Which rule explains why electrons fill degenerate (equal energy) orbitals singly before pairing?

Accepted Answer

Hund's rule

Question 11

How many valence electrons does an atom of chlorine (Cl) have?

Accepted Answer

7

Question 12

Which of the following elements is most likely to form a $$+2$$ cation to achieve noble gas configuration?

Accepted Answer

Magnesium (Mg)

Question 13

Which of the following trends is observed as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic size decreases, ionization energy increases, metallic character decreases.

Question 14

Which of the following best describes the difference between core electrons and valence electrons?

Accepted Answer

Valence electrons are in the outermost principal shell and are involved in bonding; core electrons are not.

Question 15

Which of the following electron configurations represents a transition metal in the first row of the d block?

Accepted Answer

$$[Ar]\ 4s^2$\ 3d^5$

Question 16

Which of the following statements about ionization energy is correct?

Accepted Answer

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

Question 17

A patient is undergoing radiation therapy for cancer. Which type of electromagnetic radiation is most likely being used to target the tumor?

Accepted Answer

Gamma rays

Question 18

Which of the following is a correct statement about the filling order of orbitals in multi-electron atoms?

Accepted Answer

The 4s subshell fills before the 3d subshell.

Question 19

Which of the following best explains why alkali metals are highly reactive?

Accepted Answer

They have one valence electron, which they can easily lose to achieve noble gas configuration.

Question 20

Which of the following is the correct noble gas core notation for the electron configuration of sodium (Na)?

Accepted Answer

$$[Ne]\ 3s^1$

Electrons in Atoms and the Periodic Table: Study Notes

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