Chapter 1

After 44 minutes, a sample of \(_{19}^{44} \mathrm{K}\) is found to have decayed to 25 percent of the original amount present. What is the half-life of \(_{19}^{44} \mathrm{K}?\) (A) 11 minutes (B) 22 minutes (C) 44 minutes (D) 66 minutes

Nitrogen gas was collected over water at \(25^{\circ} \mathrm{C}\) . If the vapor pressure of water at \(25^{\circ} \mathrm{C}\) is 23 \(\mathrm{mmH}\) g, and the total pressure in the container is measured at 781 \(\mathrm{mmH} \mathrm{g}\) , what is the partial pressure of the nitrogen gas? \(\begin{array}{ll}{\text { (A) }} & {46 \mathrm{mmH} \mathrm{g}} \\ {\text { (B) }} & {551 \mathrm{mmH} \mathrm{g}} \\ {\text { (C) }} & {735 \mathrm{mmH} \mathrm{g}} \\ {\text { (D) }} & {758 \mathrm{mmH} \mathrm{g}}\end{array}\)

In general, do metals or nonmetals from the same period have higher ionization energies? Why? (A) Metals have higher ionization energies because they usually have more protons than nonmetals. (B) Nonmetals have higher ionization energies because they are larger than metals and harder to ionize. (C) Metals have higher ionization energies because there is less electron shielding than there is in nonmetals. (D) Nonmetals have higher ionization energies because they are closer to having filled a complete energy level.

Use the following information to answer questions 14-16 The radius of atoms and ions is typically measured in Angstroms \((A),\) which is equivalent to \(1 * 10^{-10} \mathrm{m} .\) Below is a table of information for three different elements. TABLE NOT AVAILABLE Which of the following represents the correct electron configuration for the zinc ion, \(\mathrm{Zn}^{2+} ?\) (A) \([\mathrm{Ar}] 3 \mathrm{d}^{10}\) (B) \([\mathrm{Ar}] 4 \mathrm{s}^{2} 3 \mathrm{d}^{8}\) (C) \([\mathrm{Ar}] 4 \mathrm{s}^{2} 4 \mathrm{d}^{8}\) (D) \([\mathrm{Kr}] 4 \mathrm{s}^{2} 3 \mathrm{d}^{8}\)

\(\begin{array}{ll}{\mathrm{C}(s)+\mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)} & {\Delta H^{\circ}=-390 \mathrm{kJ} / \mathrm{mol}} \\\ {\mathrm{H}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \rightarrow \mathrm{H}_{2} \mathrm{O}(l)} & {\Delta H^{\circ}=-290 \mathrm{kJ} / \mathrm{mol}} \\ {2 \mathrm{C}(s)+\mathrm{H}_{2}(g) \rightarrow \mathrm{C}_{2} \mathrm{H}_{2}(g)} & {\Delta H^{\circ}=+230 \mathrm{kJ} / \mathrm{mol}}\end{array}\) Based on the information given above, what is \(\Delta H^{\circ}\) for the following reaction? $$ \begin{aligned} \mathrm{C}_{2} \mathrm{H}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \\ \text { (A) }-1,300 \mathrm{kJ} \\ \text { (B) }-1,070 \mathrm{kJ} \\ \text { (C) }-840 \mathrm{kJ} \\ \text { (D) }-780 \mathrm{kJ} \end{aligned} $$

A sample of a hydrate of \(\mathrm{CuSO}_{4}\) with a mass of 250 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 160 grams. What is the formula for the hydrate? (A) \(\mathrm{CuSO}_{4} \cdot 10 \mathrm{H}_{2} \mathrm{O}\) (B) \(\mathrm{CuSO}_{4} \cdot \mathrm{TH}_{2} \mathrm{O}\) (C) \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) (D) \(\mathrm{CuSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\)

A 22.0 gram sample of an unknown gas occupies 11.2 liters at standard temperature and pressure. Which of the following could be the identity of the gas? (A) \(\mathrm{CO}_{2}\) (B) \(\mathrm{SO}_{3}\) (C) \(\mathrm{O}_{2}\) (D) He

In which of the following reactions is entropy increasing? (A) \(2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightarrow 2 \mathrm{SO}_{3}(g)\) (B) \(\mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightarrow \mathrm{H}_{2}(g)+\mathrm{CO}_{2}(g)\) (C) \(\mathrm{H}_{2}(g)+\mathrm{Cl}_{2}(g) \rightarrow 2 \mathrm{HCl}(g)\) (D) \(2 \mathrm{NO}_{2}(g) \rightarrow 2 \mathrm{NO}(g)+\mathrm{O}_{2}(g)\)

The ionization energies for an element are listed in the table below. $\begin{array}{lllll}{\text { First }} & {\text { Second }} & {\text { Third }} & {\text { Fourth }} & {\text { Fifth }} \\ {8 \mathrm{eV}} & {15 \mathrm{eV}} & {80 \mathrm{eV}} & {109 \mathrm{eV}} & {141 \mathrm{eV}}\end{array}$ Based on the ionization energy table, the element is most likely to be (A) Sodium (B) Magnesium (C) Aluminum (D) Silicon

A student added 1 liter of a 1.0\(M\) \(\mathrm{KCl}\) solution to 1 liter of a 1.0 \(M\) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\) solution. A lead chloride precipitate formed, and nearly all of the lead ions disappeared from the solution. Which of the following lists the ions remaining in the solution in order of decreasing concentration? (A) \(\left[\mathrm{NO}_{3}^{-}\right]>\left[\mathrm{K}^{+}\right]>\left[\mathrm{Pb}^{2+}\right]\) (B) \(\left[\mathrm{NO}_{3}^{-}\right]>\left[\mathrm{Pb}^{2+}\right]>\left[\mathrm{K}^{+}\right]\) (C) \(\left[\mathrm{K}^{+}\right]>\left[\mathrm{Pb}^{2+}\right]>\left[\mathrm{NO}_{3}^{-}\right]\) (D) \(\left[\mathrm{K}^{+}\right]>\left[\mathrm{NO}_{3}^{-}\right]>\left[\mathrm{Pb}^{2+}\right]\)