Question 1

Which of the following best describes the difference between a scientific theory and a scientific law?

Accepted Answer

A scientific law describes a consistent relationship observed in nature, while a scientific theory explains why those relationships exist.

Question 2

A nurse needs to administer 250 mg of a medication. The available solution contains 100 mg/mL. How many milliliters should the nurse administer?

Accepted Answer

$$\frac{250\ \mathrm{mg}}{100\ \mathrm{mg/mL}} = 2.5\ \mathrm{mL}$$

Question 3

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 4

A sample of gas occupies 2.00 L at 1.00 atm and 300 K. What will be its volume at 2.00 atm and 300 K, assuming ideal gas behavior?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00\ \mathrm{atm} 	imes 2.00\ \mathrm{L}}{2.00\ \mathrm{atm}} = 1.00\ \mathrm{L}$$

Question 5

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 6

Which of the following compounds is most likely to have hydrogen bonding as its strongest intermolecular force?

Accepted Answer

H$$_2O$$

Question 7

A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 500.0 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$M = \frac{10.0\ \mathrm{g}}{58.44\ \mathrm{g/mol}} \div 0.500\ \mathrm{L} = 0.342\ \mathrm{mol/L}$$

Question 8

Which of the following best explains why water is considered a unique solvent?

Accepted Answer

Water has a high polarity and can form hydrogen bonds, allowing it to dissolve many ionic and polar substances.

Question 9

Which of the following is the correct electron configuration for a neutral atom of magnesium (atomic number 12)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$

Question 10

A chemical reaction has a $$\Delta H = -150\ \mathrm{kJ}$$ and $$\Delta S = +200\ \mathrm{J/K}. At $$what temperature (in K) does the reaction become nonspontaneous? (Recall $$\Delta G = \Delta H - T\Delta S$$; 1 kJ = 1000 J)

Accepted Answer

$$T = \frac{\Delta H}{\Delta S} = \frac{150,000\ \mathrm{J}}{200\ \mathrm{J/K}} = 750\ \mathrm{K}$$

Question 11

Which of the following best describes the role of a buffer in blood?

Accepted Answer

A buffer resists changes in pH by neutralizing added acids or bases.

Question 12

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

Accepted Answer

$$\mathrm{Ag}^+ (aq) + \mathrm{Cl}^- (aq) \rightarrow \mathrm{AgCl} (s)$$

Question 13

A 0.10 M solution of a weak acid has a pH of 3.0. What is the hydronium ion concentration $$[\mathrm{H}_3\mathrm{O}^+]$$?

Accepted Answer

$$[\mathrm{H}_3\mathrm{O}^+] = 10$$^{-3.0}$$ = 1.0 	imes 10$$^{-3}$$\ \mathrm{M}$$

Question 14

Which of the following best explains why ionic compounds generally have higher melting points than molecular compounds?

Accepted Answer

Ionic compounds have strong electrostatic forces between ions, requiring more energy to break.

Question 15

Which of the following is the correct balanced equation for the combustion of propane ($$\mathrm{C}_3\mathrm{H}_8$$)?

Accepted Answer

$$\mathrm{C}_3\mathrm{H}_8 + 5\ \mathrm{O}_2 \rightarrow 3\ \mathrm{CO}_2 + 4\ \mathrm{H}_2\mathrm{O}$$

Question 16

Which of the following statements about the kinetic molecular theory of gases is correct?

Accepted Answer

Gas particles are in constant, random motion and collisions between them are elastic.

Question 17

A buffer solution is prepared by mixing equal moles of acetic acid ($$\mathrm{CH}_3\mathrm{COOH}) $$and sodium acetate ($$\mathrm{CH}_3\mathrm{COONa}). If a $$small amount of HCl is added, what will happen to the pH?

Accepted Answer

The pH will decrease slightly, but the buffer will resist a large change.

Question 18

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

Accepted Answer

Atomic radius decreases due to increasing nuclear charge.

Question 19

A 25.0 mL sample of 0.200 M HCl is titrated with 0.100 M NaOH. What volume of NaOH is required to reach the equivalence point?

Accepted Answer

$$M_1$$ $$V_1$$ = $$M_2$$ $$V_2$$ \rightarrow (0.200\ \mathrm{M})(25.0\ \mathrm{mL}) = (0.100\ \mathrm{M})$$V_2$$ \rightarrow $$V_2 = 50.0$$\ \mathrm{mL}$$

CHE 1050 Introductory Chemistry: Comprehensive Study Guide

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