Question 1

Which of the following statements best describes the difference between Bohr orbits and quantum mechanical orbitals?

Accepted Answer

Bohr orbits are fixed circular paths for electrons, while quantum mechanical orbitals are regions of space where there is a high probability of finding an electron.

Question 2

Given the electron configuration $$1s^22s^22$p^63s^23$p^4$$, which element is this and how many unpaired electrons does it have?

Accepted Answer

Sulfur (S), 2 unpaired electrons

Question 3

Which of the following best explains why sodium forms a $$Na^+$$ ion and chlorine forms a $$Cl^-$$ ion?

Accepted Answer

Sodium loses one electron to achieve a noble gas configuration, while chlorine gains one electron to achieve a noble gas configuration.

Question 4

Which of the following molecules is predicted to have the highest boiling point based on intermolecular forces?

Accepted Answer

Isopropanol

Question 5

A sample of gas occupies 2.50 L at 1.00 atm and 25.0°C. What will the volume be at 2.00 atm and 25.0°C?

Accepted Answer

$$1.25\ \mathrm{L}$$

Question 6

Which of the following best describes the trend in atomic size across a period from left to right?

Accepted Answer

Atomic size decreases due to increasing effective nuclear charge.

Question 7

Which of the following compounds is most likely to be soluble in water?

Accepted Answer

Methanol ($$CH_3OH)$$

Question 8

What is the molarity of a solution prepared by dissolving 0.175 moles of calcium nitrate in 50.00 mL of solution?

Accepted Answer

$$3.50\ \mathrm{M}$$

Question 9

Which of the following best describes hydrogen bonding?

Accepted Answer

A special dipole-dipole interaction between hydrogen and a highly electronegative atom (O, N, or F).

Question 10

A 12.0 M HCl solution is to be diluted to make 5.00 L of a 1.50 M HCl solution. What volume of the concentrated solution is required?

Accepted Answer

$$0.625\ \mathrm{L}$$

Question 11

Which of the following best explains why $$CO_2 is a $$nonpolar molecule even though it contains polar bonds?

Accepted Answer

The molecule is linear and the bond dipoles cancel each other out.

Question 12

Which of the following is the correct Lewis structure for the ammonium ion ($$NH_4$$^+$$)?

Accepted Answer

A nitrogen atom with four single bonds to hydrogen atoms, surrounded by brackets and a positive charge.

Question 13

A gas sample has a pressure of 1.054 atm at 14.0°C. What will the pressure be when the temperature is raised to 29.7°C (at constant volume)?

Accepted Answer

$$1.111\ \mathrm{atm}$$

Question 14

Which of the following best describes the relationship between wavelength ($$\lambda$$), frequency ($$f$$), and energy ($$E) of $$electromagnetic radiation?

Accepted Answer

$$E$$ increases as $$f$$ increases and $$\lambda$$ decreases.

Question 15

Which of the following is the correct formula for calculating the density of a solution?

Accepted Answer

$$d_{sol'n} = \frac{g\ sol'n}{mL\ sol'n}$$

Question 16

Which of the following best explains why $$NaCl$$ dissolves in water but $$CCl_4$$ does not?

Accepted Answer

$$NaCl is $$ionic and water is polar, while $$CCl_4 is $$nonpolar.

Question 17

Which of the following is the correct expanded unit for molarity?

Accepted Answer

$$\frac{mol\ solute}{L\ solution}$$

Question 18

Which of the following is the correct order of increasing electronegativity for the elements F, O, N, and C?

Accepted Answer

C \u003c N \u003c O \u003c F

Question 19

A solution contains 0.087 M calcium chloride and has a volume of 0.07500 L. How many moles of calcium chloride are present?

Accepted Answer

$$0.00653\ mol$$

Question 20

Which of the following best describes why resonance structures are drawn for some molecules?

Accepted Answer

To represent the delocalization of electrons and that the true structure is an average of all resonance forms.

CHEM 101 Exam III Review: Quantum Theory, Bonding, Gases, IMFs, and Solutions

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