Question 1

A sample of an unknown element is analyzed by mass spectrometry, and the resulting spectrum shows three major peaks at mass numbers 126, 128, and 130 with nearly equal intensities. Which element is most likely present in the sample?

Accepted Answer

Tellurium ($$\mathrm{Te}$$), because it has several stable isotopes with similar abundances.

Question 2

Which of the following compounds contains the greatest mass percent of oxygen?

Accepted Answer

$$\mathrm{H_2SO_4}$$

Question 3

Atoms of potassium ($$\mathrm{K}) $$combine with atoms of chlorine ($$\mathrm{Cl}) in a 1$$:1 ratio. Which of the following statements is correct if 1 atom of K combines with 1 atom of Cl?

Accepted Answer

The resulting compound is $$\mathrm{KCl}.$$

Question 4

A student determines the percentage of silver in an alloy by dissolving it in nitric acid and precipitating the silver as $$\mathrm{AgCl} by $$adding excess $$\mathrm{NaCl}. If $$the student adds too much $$\mathrm{NaCl}$$, what is the most likely effect on the calculated percentage of silver?

Accepted Answer

The calculated percentage of silver will not be affected because the excess $$\mathrm{NaCl}$$ does not change the amount of $$\mathrm{AgCl}$$ formed.

Question 5

A certain element has two naturally occurring isotopes, with masses 35 amu (abundance 27%) and 37 amu (abundance 73%). What is the average atomic mass of this element?

Accepted Answer

$$35.54\ \mathrm{amu}$$

Question 6

Which of the following best explains why $$\mathrm{$$CaCl_2$$} is $$likely to have properties similar to $$\mathrm{$$CaBr_2$$}$$?

Accepted Answer

Both compounds contain calcium ions with a $$+2$$ charge and halide ions with a $$-1$$ charge.

Question 7

Which of the following solutions will have the greatest electrical conductivity?

Accepted Answer

0.1 M $$\mathrm{HCl} (aq)$$

Question 8

Which of the following is the best piece of laboratory glassware for preparing $$500.0\ \mathrm{mL} of a$$ $$0.100\ \mathrm{M}$$ solution?

Accepted Answer

Volumetric flask

Question 9

Which of the following is the correct balanced net ionic equation for the reaction of aqueous sodium chloride and silver nitrate?

Accepted Answer

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

Question 10

Which of the following statements about potassium iodide ($$\mathrm{KI}) is $$correct?

Accepted Answer

It contains ionic bonds.

Question 11

Which element is most likely to react in a similar fashion to sodium ($$\mathrm{Na}) $$when forming an ionic compound with chlorine ($$\mathrm{Cl}$$)?

Accepted Answer

Potassium ($$\mathrm{K})$$

Question 12

Which of the following is the empirical formula for a compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 13

Which of the following best describes the type of bond present in a $$\mathrm{Cl_2$}$$ molecule?

Accepted Answer

Covalent bond

Question 14

Which of the following is the correct name for $$\mathrm{Al_2O_3}$$?

Accepted Answer

Aluminum oxide

Question 15

A student mixes $$50.0\ \mathrm{mL} of$$ $$0.200\ \mathrm{M}$$ $$\mathrm{Ba(NO_3$)_2}$$ with $$50.0\ \mathrm{mL} of$$ $$\mathrm{$$CuSO_4$$}$$, and a precipitate forms. What is the balanced net ionic equation for the reaction?

Accepted Answer

$$\mathrm{Ba$$^{2+}$$ (aq) + SO_4$^{2-} (aq) \rightarrow $$BaSO_4$$ (s)}$$

Question 16

Which of the following best explains why $$\mathrm{H_2SO_4} is a $$strong electrolyte?

Accepted Answer

It completely ionizes in water to produce ions.

Question 17

Which of the following is the correct formula for cobalt(II) phosphate?

Accepted Answer

$$\mathrm{Co_3$(PO_4$)_2}$$

Question 18

Which of the following is the correct name for $$\mathrm{$$HClO_4$$}$$?

Accepted Answer

Perchloric acid

Question 19

Which of the following best describes the oxidation state of carbon in ethanol ($$\mathrm{C_2H_5OH}) $$when it is combusted according to the equation: $$\mathrm{C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O}$$?

Accepted Answer

Carbon is oxidized from $$-2 to$$ $$+4.$$

General Chemistry Study Guide: Chapters 1–5 (Matter, Atoms, Compounds, Reactions, Solutions, Lab Techniques)

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