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 $$2.00 	imes 10$$^{23}$$ atoms of magnesium. What is the mass of this sample? (Atomic mass of Mg = 24.3 g/mol, Avogadro's number = 6.02$$ 	imes $$10^{23}$$ mol$$^{-1})$$

Accepted Answer

$$8.08 g$$

Question 3

Which of the following electron configurations represents a neutral atom of sulfur (atomic number 16)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^4$$

Question 4

Which of the following best describes a redox reaction?

Accepted Answer

A reaction in which electrons are transferred from one species to another.

Question 5

A 0.500 L solution contains 0.250 mol NaCl. What is the molarity of the solution?

Accepted Answer

$$0.500$$ 	ext{ mol/L}$

Question 6

Which of the following changes will increase the rate of a chemical reaction?

Accepted Answer

Increasing the temperature of the reaction mixture.

Question 7

A radioactive isotope has a half-life of 3 hours. If you start with 80.0 g, how much remains after 9 hours?

Accepted Answer

$$10.0 g$$

Question 8

Which of the following is the correct formula for calculating the equilibrium constant $$K_c$$ for the reaction $$aA + bB \rightleftharpoons cC + dD$$?

Accepted Answer

$$K_c = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 9

Which of the following statements about acids and bases is correct?

Accepted Answer

A base increases the concentration of OH$$^-$$ ions in aqueous solution.

Question 10

A solution has a pH of 3. What is the concentration of H$$^+$$ ions in the solution?

Accepted Answer

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

Question 11

Which of the following best describes the Watson–Crick model of DNA structure?

Accepted Answer

Two antiparallel strands held together by hydrogen bonds between complementary base pairs.

Question 12

Which of the following is a correct statement about enzymes?

Accepted Answer

Enzymes lower the activation energy of a reaction, increasing the reaction rate.

Question 13

Which of the following is a property of alcohols?

Accepted Answer

They can form hydrogen bonds with water, making them generally soluble in water.

Question 14

Which of the following best describes the difference between D- and L-glucose?

Accepted Answer

They are mirror images of each other and differ in the configuration around the chiral carbon farthest from the carbonyl group.

Question 15

Which of the following is a correct statement about amino acids at physiological pH (about 7.4)?

Accepted Answer

They exist primarily as zwitterions, with a positively charged amino group and a negatively charged carboxyl group.

Question 16

A 250 mL sample of a 2.0 M NaOH solution is diluted to a final volume of 1.0 L. What is the new concentration?

Accepted Answer

$$0.50 M$$

Question 17

Which of the following best describes a saturated fatty acid?

Accepted Answer

A fatty acid with no carbon–carbon double bonds in its hydrocarbon chain.

Question 18

Which of the following is a correct statement about the conservation of nucleon number and charge in nuclear reactions?

Accepted Answer

The sum of the mass numbers and the sum of the atomic numbers are the same before and after the reaction.

Question 19

A student measures the length of a metal rod as 12.30 cm, 12.31 cm, and 12.29 cm in three trials. Which of the following best describes the number of significant figures in the average measurement?

Accepted Answer

Four significant figures.

Comprehensive Study Notes for General Chemistry: Atoms, Reactions, Solutions, and Biochemistry

Guida di studio - Domande di pratica

Study guide - Flashcard