Q: A student dissolves 5.00 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? ($$M = \frac{\text{moles solute}}{\text{liters solution}}$$; molar mass NaCl = 58.44 g/mol)

$$M = \frac{5.00\,\text{g}}{58.44\,\text{g/mol}} \div 0.250\,\text{L} = 0.342\,\text{M}$$

Q: A sample contains 0.50 mol of H$$_2$$ and 1.00 mol of O$$_2. If $$the gases are combined and react completely to form water, what mass of water is produced? ($$2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$$; molar mass H$$_2O = 18.02 g/$$mol)

18.02 g (limiting reactant is H$$_2$$: $$0.50\,\text{mol} \times 18.02\,\text{g/mol} = 9.01\,\text{g})$$

Q: Which of the following is the correct net ionic equation for the reaction between aqueous solutions of Na$$_2SO$_4$$ and BaCl$$_2$$?

$$\text{Ba}^{2+}(aq) + \text{SO}_4$$^{2-}$$(aq) \rightarrow \text{BaSO}_4(s)$$

Question 1

Which statement best describes the difference between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically bonded in fixed proportions, while a mixture contains two or more substances physically combined in variable proportions.

Question 2

Which of the following best explains why ice floats on water?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonding creates an open hexagonal structure.

Question 3

A student dissolves 5.00 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? ($$M = \frac{	ext{moles solute}}{	ext{liters solution}}$$; molar mass NaCl = 58.44 g/mol)

Accepted Answer

$$M = \frac{5.00\,	ext{g}}{58.44\,	ext{g/mol}} \div 0.250\,	ext{L} = 0.342\,	ext{M}$$

Question 4

Which of the following is a correct statement about the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 5

Which of the following best describes the difference between an empirical formula and a molecular formula?

Accepted Answer

The empirical formula shows the simplest whole-number ratio of atoms, while the molecular formula shows the actual number of atoms in a molecule.

Question 6

A sample contains 0.50 mol of H$$_2$$ and 1.00 mol of O$$_2. If $$the gases are combined and react completely to form water, what mass of water is produced? ($$2	ext{H}_2 + 	ext{O}_2 ightarrow 2	ext{H}_2	ext{O}$$; molar mass H$$_2O = 18.02 g/$$mol)

Accepted Answer

18.02 g (limiting reactant is H$$_2$$: $$0.50\,	ext{mol} 	imes 18.02\,	ext{g/mol} = 9.01\,	ext{g})$$

Question 7

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 8

Which of the following best explains why noble gases are chemically inert?

Accepted Answer

Noble gases have completely filled valence electron shells, making them stable and unreactive.

Question 9

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of Na$$_2SO$_4$$ and BaCl$$_2$$?

Accepted Answer

$$	ext{Ba}^{2+}(aq) + 	ext{SO}_4$$^{2-}$$(aq) ightarrow 	ext{BaSO}_4(s)$$

Question 10

Which of the following best describes the process of calculating the empirical formula from percent composition?

Accepted Answer

Convert each element's percent to grams, then to moles, divide by the smallest number of moles, and use the resulting ratio as subscripts.

Question 11

Which of the following statements about the photoelectric effect is correct?

Accepted Answer

Electrons are ejected from a metal surface only if the incident light has a frequency above a certain threshold, regardless of intensity.

Question 12

Which of the following is the correct electron configuration for a neutral atom of sulfur (S, atomic number 16)?

Accepted Answer

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

Question 13

Which of the following best explains why atomic radius decreases across a period from left to right?

Accepted Answer

Increasing nuclear charge pulls electrons closer to the nucleus, reducing atomic size.

Question 14

Which of the following is the correct formula for calculating the energy of a photon?

Accepted Answer

$$E = h 
u$$

Question 15

Which of the following best describes the difference between ionic and covalent compounds?

Accepted Answer

Ionic compounds are formed from the transfer of electrons between metals and nonmetals, while covalent compounds are formed from the sharing of electrons between nonmetals.

Question 16

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

Accepted Answer

$$PV = nRT$$

Question 17

A sample of gas occupies 2.00 L at 1.00 atm and 300 K. If the pressure is increased to 2.00 atm at constant temperature, what is the new volume? ($$P_1V_1 = P_2V_2)$$

Accepted Answer

1.00 L

Question 18

Which of the following best explains why water has a high boiling point compared to other group 16 hydrides?

Accepted Answer

Water molecules form strong hydrogen bonds due to high polarity and small size.

Question 19

Which of the following is the correct formula for calculating the percent yield of a chemical reaction?

Accepted Answer

$$	ext{Percent yield} = \frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\%$$

General Chemistry I: Comprehensive Study Guide (Chapters 1–13)

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