Q: Which of the following is the correct order of increasing ionic radius for the ions: $$\text{O}^{2-}$$, $$\text{Mg}^{2+}$$, $$\text{S}^{2-}$$, $$\text{Ca}^{2+}$$?

$$\text{Mg}^{2+} \u003c \text{Ca}^{2+} \u003c \text{O}^{2-} \u003c \text{S}^{2-}$$

Question 1

Which of the following statements best explains why the third ionization energy of magnesium is much higher than its first and second ionization energies?

Accepted Answer

The third electron is removed from a completely filled s subshell, which is more stable.

Question 2

A 0.287 nm wavelength X-ray photon strikes a metal surface, ejecting an electron with a kinetic energy of 715 eV. What is the binding energy of the electron in kJ/mol? (Use $$E = \frac{hc}{\lambda}$$, $$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s$$, $$1\ 	ext{eV} = 1.602 	imes 10$$^{-19}$$ J, N_A = 6.022$$ 	imes $$10^{23}$$ mol$$^{-1})$$

Accepted Answer

$$2.13 	imes 10^5$ kJ/mol

Question 3

Which of the following best describes the trend in atomic radius as you move from left to right across a period in the periodic table?

Accepted Answer

Atomic radius decreases due to increasing nuclear charge pulling electrons closer.

Question 4

Which of the following ions is isoelectronic with Ne?

Accepted Answer

$$	ext{Mg}^{2+}$$

Question 5

The electron affinity of thulium is measured using a laser with a wavelength of 1064 nm, and the ejected electrons have an energy of 0.137 eV. What is the electron affinity of thulium in eV per atom? (Use $$E = \frac{hc}{\lambda}$$, $$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s$$, $$1\ 	ext{eV} = 1.602 	imes 10$$^{-19}$$ J)

Accepted Answer

1.03 eV

Question 6

Which of the following best explains why the first ionization energy of sodium is much lower than that of magnesium?

Accepted Answer

Sodium has a single valence electron in a higher energy level, making it easier to remove.

Question 7

Which of the following statements about the Bohr model of the atom is correct?

Accepted Answer

It explains the quantized energy levels of hydrogen but fails for multi-electron atoms.

Question 8

Which set of quantum numbers is not allowed for an electron in an atom?

Accepted Answer

$$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 9

Which of the following electron configurations represents a paramagnetic species?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^3$$

Question 10

Which of the following best describes the effect of crystalline lattice energy on the formation of an ionic compound?

Accepted Answer

A higher lattice energy makes the formation of the ionic compound more exothermic.

Question 11

Which of the following transitions in the hydrogen atom will emit the photon with the shortest wavelength?

Accepted Answer

$$n=5 to$$ $$n=1$$

Question 12

Which of the following best describes the dual nature of light?

Accepted Answer

Light exhibits both wave-like and particle-like properties.

Question 13

Which of the following is the correct electron configuration for the $$	ext{O}^{2-}$$ ion?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 14

Which of the following best explains why the removal of an electron from the $$n=2$$ shell is harder than from the $$n=3$$ shell?

Accepted Answer

Electrons in the $$n=2$$ shell are closer to the nucleus and experience a stronger electrostatic attraction.

Question 15

Which of the following best describes the relationship between wavelength and energy for electromagnetic radiation?

Accepted Answer

As wavelength decreases, energy increases.

Question 16

Which of the following is the correct order of increasing ionic radius for the ions: $$	ext{O}^{2-}$$, $$	ext{Mg}^{2+}$$, $$	ext{S}^{2-}$$, $$	ext{Ca}^{2+}$$?

Accepted Answer

$$	ext{Mg}^{2+} \u003c 	ext{Ca}^{2+} \u003c 	ext{O}^{2-} \u003c 	ext{S}^{2-}$$

Question 17

Which of the following best describes the effect of increasing nuclear charge on ionization energy?

Accepted Answer

Increasing nuclear charge increases ionization energy.

Question 18

Which of the following is a consequence of the Heisenberg uncertainty principle?

Accepted Answer

It is impossible to know both the exact position and momentum of an electron simultaneously.

Question 19

Which of the following best describes the process of photoelectron spectroscopy (PES)?

Accepted Answer

PES measures the binding energies of electrons by ejecting them with photons and analyzing their kinetic energies.

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