Question 1

A solution is prepared by dissolving 15.0 g of NaOH in enough water to make 250 mL of solution. What is the molarity of the solution? (Molar mass of NaOH = 40.0 g/mol)

Accepted Answer

$$0.60\ \mathrm{M}$$

Question 2

How many grams of KCl are needed to prepare 500 mL of a 0.200 M KCl solution? (Molar mass of KCl = 74.6 g/mol)

Accepted Answer

$$7.46\ \mathrm{g}$$

Question 3

Which of the following best describes a saturated solution?

Accepted Answer

A solution in which no more solute can dissolve at a given temperature.

Question 4

Which of the following is the correct balanced nuclear equation for the alpha decay of Uranium-238?

Accepted Answer

$$^{238}_{92}\mathrm{U} \$$rightarrow ^{234}$$_{90}\mathrm{Th} $$+ ^{4}$$_{2}\mathrm{He}$$

Question 5

Which statement correctly compares nuclear fission and fusion?

Accepted Answer

Fission splits a heavy nucleus into lighter nuclei (e.g., $$^{235}\mathrm{U} in $$reactors), while fusion combines light nuclei to form a heavier nucleus (e.g., $$^2\mathrm{H} + ^3$\mathrm{H} \$$rightarrow ^4$$\mathrm{He} in $$stars).

Question 6

A radioactive isotope has a half-life of 6.0 hours. If you start with 80.0 g, how much remains after 18 hours?

Accepted Answer

$$10.0\ \mathrm{g}$$

Question 7

Rank the following intermolecular forces in order of increasing strength: London dispersion, dipole-dipole, hydrogen bonding.

Accepted Answer

London dispersion \u003c Dipole-dipole \u003c Hydrogen bonding

Question 8

Which compound has the higher boiling point, $$\mathrm{H_2O} or$$ $$\mathrm{H_2S}$$, and why?

Accepted Answer

$$\mathrm{H_2O}$$, because it forms hydrogen bonds.

Question 9

Why does ice float on liquid water?

Accepted Answer

Because hydrogen bonding causes ice to have an open, less dense structure.

Question 10

Which of the following correctly matches each quantum number with what it describes?

Accepted Answer

n: energy level; l: orbital shape; m_l: orbital orientation; m_s: electron spin

Question 11

For an electron with $$n = 3$$, $$l = 2$$, what are the possible values of $$m_l$$ and $$m_s$$?

Accepted Answer

$$m_l = -2, -1, 0, +1, +2$$; $$m_s = +\frac{1}{2}, -\frac{1}{2}$$

Question 12

A patient receives a dose of a radioactive tracer with a half-life of 3 hours. If the initial dose is 32 mg, how much remains after 9 hours?

Accepted Answer

$$4\ \mathrm{mg}$$

Question 13

Which of the following best explains why salt (NaCl) dissolves in water but not in oil?

Accepted Answer

Because water is polar and can stabilize the ions, while oil is nonpolar and cannot.

Question 14

Which of the following is a real-life example of nuclear fusion?

Accepted Answer

The production of energy in the sun by combining hydrogen nuclei.

Question 15

A student adds sugar to water until no more dissolves and some remains at the bottom. What type of solution is this?

Accepted Answer

Saturated

Question 16

Which of the following molecules can form hydrogen bonds with water?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 17

Which intermolecular force is present in all molecular substances, regardless of polarity?

Accepted Answer

London dispersion forces

Question 18

A chemist needs to prepare 1.00 L of 0.500 M NaCl solution. How many grams of NaCl are required? (Molar mass of NaCl = 58.5 g/mol)

Accepted Answer

$$29.3\ \mathrm{g}$$

GOB Chemistry Study Guide: Solutions, Nuclear Reactions, Intermolecular Forces, and Quantum Numbers

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