Question 1

Which of the following observations is NOT evidence that a chemical reaction has occurred?

Accepted Answer

A liquid evaporates when left in an open container.

Question 2

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

Accepted Answer

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

Question 3

Which of the following compounds is a strong electrolyte when dissolved in water?

Accepted Answer

$$\mathrm{NaCl} ($$sodium chloride)

Question 4

A student mixes solutions of $$\mathrm{$$AgNO_3$$}$$ and $$\mathrm{NaCl}. $$Which of the following is the correct net ionic equation for the precipitation reaction that occurs?

Accepted Answer

$$\mathrm{Ag^+} (aq) + \mathrm{Cl^-} (aq) \rightarrow \mathrm{AgCl} (s)$$

Question 5

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

Accepted Answer

$$\mathrm{2H_2} (g) + \mathrm{O_2$} (g) \rightarrow 2\mathrm{H_2O} (l)$$

Question 6

Assign the oxidation state of sulfur in $$\mathrm{H_2SO_4}.$$

Accepted Answer

+6

Question 7

Which of the following best describes a synthesis (combination) reaction?

Accepted Answer

Two or more substances combine to form a single product.

Question 8

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

Accepted Answer

It is caused by the absorption of infrared radiation by gases such as $$\mathrm{CO_2$} in $$the atmosphere.

Question 9

How many moles of $$\mathrm{CO_2$}$$ are produced when 2.0 moles of $$\mathrm{C_2H_6}$$ are combusted completely according to the equation:

$$2\mathrm{C_2H_6} + 7\mathrm{O_2$} \rightarrow 4\mathrm{CO_2$} + 6\mathrm{H_2O}$$?

Accepted Answer

4.0 moles

Question 10

A reaction has a theoretical yield of 10.0 g and an actual yield of 7.5 g. What is the percent yield?

Accepted Answer

$$75\%$$

Question 11

Which of the following statements about enthalpy ($$\Delta H_{rxn}) is $$correct?

Accepted Answer

A negative $$\Delta H_{rxn}$$ indicates that the reaction is exothermic.

Question 12

Which of the following best describes the Bohr model of the atom?

Accepted Answer

Electrons orbit the nucleus in fixed energy levels.

Question 13

Which quantum number determines the energy level of an electron in an atom?

Accepted Answer

Principal quantum number ($$n)$$

Question 14

What is the ground-state electron configuration for $$\mathrm{Na} ($$sodium, atomic number 11)?

Accepted Answer

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

Question 15

Which element has the highest first ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 16

Which of the following statements about periodic trends in atomic radius is correct?

Accepted Answer

Atomic radius decreases across a period from left to right.

Question 17

Which of the following ions has the same electron configuration as argon ($$\mathrm{Ar}$$)?

Accepted Answer

$$\mathrm{Cl^-}$$

Question 18

Which of the following best describes the Pauli Exclusion Principle?

Accepted Answer

No two electrons in an atom can have the same set of four quantum numbers.

Question 19

Which of the following is a decomposition reaction?

Accepted Answer

$$2\mathrm{$$KClO_3$$} \rightarrow 2\mathrm{KCl} + 3\mathrm{O_2$}$$

Question 20

A sample of magnesium reacts with hydrochloric acid to produce hydrogen gas according to the equation:

$$\mathrm{Mg} (s) + 2\mathrm{HCl} (aq) \rightarrow \mathrm{$$MgCl_2$$} (aq) + \mathrm{H_2$} (g)

If 2.00 g of$$ $$\mathrm{Mg} is $$reacted with 10.0 g of $$\mathrm{HCl}$$, which reactant is the limiting reactant? (Molar masses: $$\mathrm{Mg} = 24.3\ \mathrm{g/mol}$$, $$\mathrm{HCl} = 36.5\ \mathrm{g/mol})$$

Accepted Answer

$$\mathrm{HCl}$$

CHM1032 Study Notes: Chemical Reactions, Stoichiometry, and Atomic Structure (Chapters 7, 8, and 9)

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