Question 1

Which of the following best describes a chemical bond according to molecular orbital (MO) theory?

Accepted Answer

A chemical bond forms when atomic orbitals overlap to create molecular orbitals that are lower in energy than the original atomic orbitals.

Question 2

Which of the following molecules is predicted to be paramagnetic according to molecular orbital theory?

Accepted Answer

$$\mathrm{O_2$}$$

Question 3

What is the bond order of the $$\mathrm{N_2$}$$ molecule according to molecular orbital theory?

Accepted Answer

$$3$$

Question 4

Which of the following statements about delocalized orbitals and resonance is correct?

Accepted Answer

Delocalized orbitals allow electrons to be shared over more than two atoms, which is represented by resonance structures.

Question 5

A student is asked to determine the empirical formula of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 6

Which of the following best explains why $$\mathrm{O_2$} is $$paramagnetic?

Accepted Answer

Because it has unpaired electrons in its $$\pi^*$$ antibonding molecular orbitals.

Question 7

A 10.0 g sample of a compound contains 2.0 g of hydrogen and 8.0 g of oxygen. What is the percent composition of hydrogen in the compound?

Accepted Answer

$$20\%$$

Question 8

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

Accepted Answer

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

Question 9

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$\mathrm{M_{NaCl}} = 58.44\ \mathrm{g/mol})$$

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 10

Which of the following best describes a strong electrolyte?

Accepted Answer

A substance that dissolves in water and produces a solution that conducts electricity very well because it completely dissociates into ions.

Question 11

Which of the following statements about balancing chemical equations is correct?

Accepted Answer

You can only balance a chemical equation by changing the coefficients in front of the chemical formulas.

Question 12

A reaction has a theoretical yield of 10.0 g, but only 7.5 g of product is actually obtained. What is the percent yield?

Accepted Answer

$$75\%$$

Question 13

Which of the following is an example of an oxidation-reduction (redox) reaction?

Accepted Answer

$$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$

Question 14

Which of the following best describes the difference between a physical change and a chemical change?

Accepted Answer

A chemical change results in the formation of new substances, while a physical change does not.

Question 15

Which of the following is the correct electron configuration for the $$\mathrm{O_2$}$$ molecule using molecular orbital theory?

Accepted Answer

$$\sigma_{2s}^2\ \sigma_{2s}^{*2}\ \sigma_{2p_z}^2\ \pi_{2p_x}^2\ \pi_{2p_y}^2\ \pi_{2p_x}^{*1}\ \pi_{2p_y}^{*1}$$

Question 16

A 500.0 mL solution contains 0.250 mol of $$\mathrm{KBr}. $$What is the molarity of the solution?

Accepted Answer

$$0.125\ \mathrm{M}$$

Question 17

Which of the following best describes the difference between a strong acid and a weak acid in aqueous solution?

Accepted Answer

A strong acid completely ionizes in water, while a weak acid only partially ionizes.

Question 18

Which of the following statements about molecular orbitals in heteronuclear diatomic molecules is correct?

Accepted Answer

The atomic orbitals from different atoms may have different energies, which affects the energies and character of the resulting molecular orbitals.

Question 19

A student mixes solutions of $$\mathrm{$$AgNO_3$$}$$ and $$\mathrm{NaCl}$$ and observes the formation of a white precipitate. Which type of reaction has occurred?

Accepted Answer

Precipitation reaction

General Chemistry Study Guide: Chemical Bonding, Chemical Formulas, Chemical Equations, and Aqueous Reactions

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