Q: Which of the following is the correct formula for calculating the molarity ($$M) of a $$solution?

$$M = \dfrac{\text{moles of solute}}{\text{volume of solution in liters}}$$

Question 1

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

Accepted Answer

Ionic compounds are formed by transferring electrons between atoms, while covalent compounds are formed by sharing electrons.

Question 2

Which subatomic particle is responsible for the chemical properties of an element?

Accepted Answer

Electron

Question 3

A student mixes 50.0 mL of 0.20 M NaOH with 50.0 mL of 0.20 M HCl. What is the pH of the resulting solution?

Accepted Answer

pH = 7

Question 4

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}) in $$oxygen?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 5

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence electron shell, making them stable.

Question 6

A sample contains 3.0 moles of $$\mathrm{NaCl}. $$How many formula units of $$\mathrm{NaCl}$$ are present in the sample? ($$\mathrm{N_A = 6.022 	imes 10$$^{23}$$})$$

Accepted Answer

$$1.81 	imes 10$$^{24}$$

Question 7

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

Accepted Answer

Acids donate protons, while bases accept protons.

Question 8

Which of the following is the correct electron configuration for a neutral oxygen atom?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^4$$

Question 9

A solution is prepared by dissolving 5.0 g of $$\mathrm{NaCl} in $$enough water to make 250 mL of solution. What is the molarity of the solution? ($$\mathrm{M_{NaCl} = 58.44\ g/mol})$$

Accepted Answer

$$0.34\ \mathrm{M}$$

Question 10

Which of the following best describes the process of reduction in a chemical reaction?

Accepted Answer

Gain of electrons by an atom or ion.

Question 11

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine

Question 12

A gas occupies 2.0 L at 1.0 atm. If the pressure is increased to 4.0 atm at constant temperature, what is the new volume?

Accepted Answer

0.5 L

Question 13

Which of the following is a correct statement about isotopes?

Accepted Answer

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

Question 14

Which of the following is the correct formula for calculating the molarity ($$M) of a $$solution?

Accepted Answer

$$M = \dfrac{	ext{moles of solute}}{	ext{volume of solution in liters}}$$

Question 15

Which of the following best describes a buffer solution?

Accepted Answer

A solution that resists changes in pH when small amounts of acid or base are added.

Question 16

Which of the following is the correct balanced equation for the reaction of hydrochloric acid with sodium hydroxide?

Accepted Answer

$$\mathrm{HCl + NaOH \rightarrow NaCl + H_2O}$$

Question 17

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, creating a partial negative charge on oxygen and a partial positive charge on hydrogen.

Question 18

A radioactive isotope has a half-life of 10 years. If you start with 80 g, how much remains after 30 years?

Accepted Answer

10 g

Question 19

Which of the following is the correct formula for the ideal gas law?

Accepted Answer

$$PV = nRT$$

Question 20

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

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