Question 1

Which of the following statements best explains why isotopes of the same element have nearly identical chemical properties?

Accepted Answer

Because isotopes have the same number of protons and electrons, which determine chemical behavior.

Question 2

A sample contains 18.0 grams of water ($$\mathrm{H_2O}). $$How many moles of water are present in the sample? (Molar mass of $$\mathrm{H_2O}$$ = $$18.0\ \mathrm{g/mol})$$

Accepted Answer

$$1.0$$ mole

Question 3

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

Accepted Answer

Atomic radius decreases due to increasing nuclear charge pulling electrons closer.

Question 4

Which of the following electron configurations represents a neutral atom of magnesium ($$\mathrm{Mg}$$, atomic number $$12$$)?

Accepted Answer

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

Question 5

A patient receives an intravenous solution containing $$0.90\ \mathrm{g} of $$sodium chloride ($$\mathrm{NaCl}) $$dissolved in $$100\ \mathrm{mL} of $$water. What is the mass/volume percent ($$\%\ m/v) of$$ $$\mathrm{NaCl} in $$the solution?

Accepted Answer

$$0.90\%$$

Question 6

Which of the following best explains why ionic compounds conduct electricity when dissolved in water but not in solid form?

Accepted Answer

Because ions are free to move in solution, allowing charge to flow.

Question 7

Which of the following is the correct IUPAC name for the compound with the formula $$\mathrm{C_3H_8}$$?

Accepted Answer

Propane

Question 8

A solution is prepared by diluting $$25\ \mathrm{mL} of a$$ $$2.0\ \mathrm{M}$$ hydrochloric acid ($$\mathrm{HCl}) $$stock solution to a final volume of $$100\ \mathrm{mL}. $$What is the final concentration of $$\mathrm{HCl}$$?

Accepted Answer

$$0.50\ \mathrm{M}$$

Question 9

Which of the following best describes the role of a buffer solution in the human body?

Accepted Answer

It resists changes in pH when small amounts of acid or base are added.

Question 10

Which of the following statements about the law of definite proportions is correct?

Accepted Answer

A given compound always contains the same elements in the same fixed ratio by mass.

Question 11

Which of the following best explains why phenol is more acidic than ethanol?

Accepted Answer

The phenoxide ion formed after deprotonation is stabilized by resonance over the aromatic ring.

Question 12

Which of the following is a correct statement about the structure of DNA according to the Watson–Crick model?

Accepted Answer

DNA consists of two antiparallel strands held together by complementary base pairing.

Question 13

Which of the following reactions is an example of a redox reaction important in cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\ \mathrm{O_2$} \rightarrow 6\ \mathrm{CO_2$} + 6\ \mathrm{H_2O}$$

Question 14

A radioactive isotope has a half-life of $$3$$ hours. If you start with $$80\ \mathrm{mg}$$, how much remains after $$9$$ hours?

Accepted Answer

$$10\ \mathrm{mg}$$

Question 15

Which of the following best describes the difference between a saturated and an unsaturated fatty acid?

Accepted Answer

Saturated fatty acids have no double bonds; unsaturated fatty acids have one or more double bonds.

Question 16

Which of the following best explains why enzymes are highly specific in their action?

Accepted Answer

The three-dimensional shape of the enzyme's active site matches only specific substrates.

Question 17

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

Accepted Answer

$$\mathrm{pH} = -\log [\mathrm{H}^+]$$

Question 18

Which of the following best describes the role of disulfide bonds in proteins?

Accepted Answer

They stabilize the tertiary and quaternary structure by forming covalent links between cysteine residues.

Question 19

A $$0.10\ \mathrm{M}$$ solution of acetic acid ($$\mathrm{CH_3COOH}) is $$partially dissociated in water. Which of the following statements is true regarding its acid strength and dissociation?

Accepted Answer

Acetic acid is a weak acid and only partially dissociates in water.

Comprehensive Study Notes for General Chemistry: Foundations for Medical and Biological Sciences

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