$$2 \times 23.0 + 32.1 + 4 \times 16.0 = 142.1$$

Question 1

Which statement best describes the law of constant composition as it applies to water?

Accepted Answer

All samples of pure water contain hydrogen and oxygen in a fixed mass ratio of $$8.0:1.$$

Question 2

Which of the following is a correct chemical formula for a compound containing magnesium and nitrate ions?

Accepted Answer

$$\mathrm{Mg(NO_3$)_2}$$

Question 3

What is the empirical formula for hydrogen peroxide, whose molecular formula is $$\mathrm{H_2O_2}$$?

Accepted Answer

$$\mathrm{HO}$$

Question 4

Which of the following compounds is classified as an ionic compound?

Accepted Answer

$$\mathrm{NaCl}$$

Question 5

How many oxygen atoms are present in one formula unit of $$\mathrm{Al_2$(SO_4$)_3}$$?

Accepted Answer

12

Question 6

Which of the following is the correct name for $$\mathrm{$$FeCl_2$$}$$?

Accepted Answer

Iron(II) chloride

Question 7

What is the formula mass of $$\mathrm{Na_2SO_4}$$? (Atomic masses: Na = 23.0, S = 32.1, O = 16.0)

Accepted Answer

$$2 	imes 23.0 + 32.1 + 4 	imes 16.0 = 142.1$$

Question 8

Which of the following is the correct systematic name for $$\mathrm{$$KNO_3$$}$$?

Accepted Answer

Potassium nitrate

Question 9

Which of the following elements exists naturally as a diatomic molecule?

Accepted Answer

Nitrogen

Question 10

What is the correct name for $$\mathrm{H_2SO_3(aq)}$$?

Accepted Answer

Sulfurous acid

Question 11

Which of the following best explains why the properties of sodium chloride differ from those of sodium and chlorine?

Accepted Answer

The elements in sodium chloride combine in fixed, definite proportions, resulting in new properties.

Question 12

Which of the following is the correct formula for aluminum oxide, given the charges $$\mathrm{Al$$^{3+}$$}$$ and $$\mathrm{O$$^{2-}$$}$$?

Accepted Answer

$$\mathrm{Al_2O_3}$$

Question 13

Which of the following is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 14

Which of the following acids is responsible for acid rain formed from coal-powered electricity generation?

Accepted Answer

Sulfuric acid

Question 15

How many nitrogen atoms are present in one formula unit of $$\mathrm{(NH_4$)_2SO_4}$$?

Accepted Answer

2

Question 16

Which of the following is the correct name for $$\mathrm{Cu(NO_3$)_2}$$?

Accepted Answer

Copper(II) nitrate

Question 17

Which of the following is the correct formula for calcium phosphate, given the ions $$\mathrm{Ca$$^{2+}$$}$$ and $$\mathrm{PO_4$^{3-}}$$?

Accepted Answer

$$\mathrm{Ca_3$(PO_4$)_2}$$

Question 18

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

Accepted Answer

Perchloric acid

Question 19

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound contains elements in fixed, definite proportions; a mixture can have variable proportions.

Question 20

What is the correct name for $$\mathrm{SO_3$}$$?

Accepted Answer

Sulfur trioxide

Chapter 5: Molecules and Compounds – Study Notes for Introductory Chemistry

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