Q: Which of the following statements about the photoelectric effect is correct?

Electrons are emitted from a metal surface only if the light has a frequency above a certain threshold.

Q: Which of the following best explains why successive ionization energies increase for an atom?

Each electron removed experiences a stronger effective nuclear charge.

Question 1

Which of the following statements best explains why the atomic radius decreases across a period from left to right in the periodic table?

Accepted Answer

The nuclear charge increases, pulling electrons closer to the nucleus.

Question 2

A photon has a wavelength of $4.00 	imes 10^{-7}$ m. What is the energy of this photon? (Use $c = 3.00 	imes 10^8$ m/s and $h = 6.63 	imes 10^{-34}$ J·s)

Accepted Answer

$4.97 	imes 10^{-19}$ J

Question 3

Which of the following electron configurations represents a violation of the Pauli exclusion principle?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 3d^2$ (with both electrons in 3d having the same spin)

Question 4

Which element in the third period of the periodic table has the highest first ionization energy?

Accepted Answer

Chlorine ($Cl$)

Question 5

What is the relationship between the frequency ($
u$), wavelength ($\lambda$), and speed of light ($c$) for electromagnetic radiation?

Accepted Answer

$c = \lambda 
u$

Question 6

Which of the following best describes Hund's rule?

Accepted Answer

Electrons occupy degenerate orbitals singly before pairing.

Question 7

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($l$)

Question 8

Which of the following transitions in the hydrogen atom emits the highest energy photon?

Accepted Answer

From $n=2$ to $n=1$

Question 9

Which of the following ions has the smallest radius?

Accepted Answer

$Mg^{2+}$

Question 10

Which statement correctly describes the trend in ionization energy across a period?

Accepted Answer

Ionization energy increases due to increasing nuclear charge.

Question 11

What is the de Broglie wavelength of an electron moving at $2.00 	imes 10^6$ m/s? (Mass of electron $= 9.11 	imes 10^{-31}$ kg, $h = 6.63 	imes 10^{-34}$ J·s)

Accepted Answer

$3.64 	imes 10^{-10}$ m

Question 12

Which of the following elements has the most negative electron affinity?

Accepted Answer

Fluorine ($F$)

Question 13

Which of the following best explains why cations are smaller than their parent atoms?

Accepted Answer

Cations have fewer electrons, resulting in less electron-electron repulsion.

Question 14

Which of the following is the correct condensed electron configuration for $Ar$ (Argon)?

Accepted Answer

$[Ne] 3s^2 3p^6$

Question 15

Which of the following best describes the uncertainty principle?

Accepted Answer

It is impossible to know both the position and momentum of an electron exactly at the same time.

Question 16

Which of the following elements has the largest atomic radius?

Accepted Answer

Potassium ($K$)

Question 17

Which of the following best describes the process of ionization energy?

Accepted Answer

The energy required to remove an electron from a neutral atom.

Question 18

Which of the following is the correct order of increasing atomic radius for the elements $Na$, $Mg$, $Al$, and $Si$?

Accepted Answer

$Si < Al < Mg < Na$

Question 19

Which of the following statements about the photoelectric effect is correct?

Accepted Answer

Electrons are emitted from a metal surface only if the light has a frequency above a certain threshold.

Question 20

Which of the following best explains why successive ionization energies increase for an atom?

Accepted Answer

Each electron removed experiences a stronger effective nuclear charge.

Quantum Mechanics, Electron Configuration, and Periodic Trends in General Chemistry

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