Question 1

Which of the following best describes the difference between an ionic and a molecular compound?

Accepted Answer

Ionic compounds are formed by the transfer of electrons from metals to nonmetals, resulting in charged ions, while molecular compounds are formed by the sharing of electrons between nonmetals.

Question 2

A patient receives a dose of medication that is 0.250 grams. What is this mass in milligrams ($$1 \ \mathrm{g} = 1000 \ \mathrm{mg}$$)?

Accepted Answer

$$250 \ \mathrm{mg}$$

Question 3

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 4

A radioactive isotope decays with a half-life of 8 hours. If you start with $$100 \ \mathrm{mg}$$, how much remains after 24 hours?

Accepted Answer

$$25 \ \mathrm{mg}$$

Question 5

Which of the following best explains why water is a good solvent for ionic compounds?

Accepted Answer

Water is polar and can stabilize the positive and negative ions formed when ionic compounds dissolve.

Question 6

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

Accepted Answer

$$0.171 \ \mathrm{M}$$

Question 7

Which of the following is a correct balanced equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8} + 5\mathrm{O_2$} \rightarrow 3\mathrm{CO_2$} + 4\mathrm{H_2O}$$

Question 8

A buffer solution is made by mixing acetic acid and sodium acetate. What is the primary function of this buffer in a biological system?

Accepted Answer

To keep the pH nearly constant when small amounts of acid or base are added.

Question 9

Which of the following functional groups is present in all amino acids?

Accepted Answer

A carboxyl group ($$-\mathrm{COOH}) $$and an amino group ($$-\mathrm{NH_2$})$$

Question 10

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy of biochemical reactions, increasing the reaction rate.

Question 11

A patient is given a saline IV solution that is isotonic to blood. What would happen if a hypotonic solution were used instead?

Accepted Answer

Red blood cells would swell and possibly burst due to water entering the cells.

Question 12

Which of the following statements about carbohydrates is correct?

Accepted Answer

Carbohydrates are organic molecules containing carbon, hydrogen, and oxygen, often in a 1:2:1 ratio.

Question 13

Which of the following best describes the structure of a triglyceride (a common lipid)?

Accepted Answer

Three fatty acids bonded to a glycerol molecule.

Question 14

Which of the following is a correct statement about nucleic acids?

Accepted Answer

Nucleic acids are composed of nucleotides, each containing a sugar, a phosphate group, and a nitrogenous base.

Question 15

A sample of gas occupies $$2.00 \ \mathrm{L} at$$ $$1.00 \ \mathrm{atm}$$ and $$300 \ \mathrm{K}. If $$the pressure is increased to $$2.00 \ \mathrm{atm}$$ and the temperature is increased to $$600 \ \mathrm{K}$$, what is the new volume? (Assume ideal gas behavior.)

Accepted Answer

$$2.00 \ \mathrm{L}$$

Question 16

Which of the following is a correct statement about acids and bases according to the Brønsted-Lowry definition?

Accepted Answer

An acid is a substance that donates a proton ($$\mathrm{H^+}$$), and a base is a substance that accepts a proton.

Question 17

Which of the following best explains why carbon is uniquely suited to form the backbone of organic molecules?

Accepted Answer

Carbon can form four strong covalent bonds, allowing for a variety of stable structures.

Question 18

A solution has a pH of 3. What is the concentration of hydronium ions ($$[\mathrm{H_3O^+}]) in $$the solution?

Accepted Answer

$$1 	imes 10$$^{-3}$$ \ \mathrm{M}$$

Question 19

Which of the following is a correct statement about protein structure?

Accepted Answer

The primary structure of a protein is the sequence of amino acids linked by peptide bonds.

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