Question 1

Which statement best describes the law of constant composition?

Accepted Answer

All samples of a given compound have the same proportions of their constituent elements.

Question 2

If you decompose 36.0 g of water, how many grams of oxygen and hydrogen would you expect to obtain, based on the law of constant composition?

Accepted Answer

32.0 g O and 4.0 g H

Question 3

Which of the following is a correct chemical formula for table sugar (sucrose)?

Accepted Answer

$$\mathrm{C$$_{12}$$H_{22}O$$_{11}}$

Question 4

What is the mass ratio of nitrogen to hydrogen in ammonia ($$\mathrm{NH_3$}$$)?

Accepted Answer

$$\frac{14.0\ \mathrm{g\ N}}{3.0\ \mathrm{g\ H}} = 4.7:1$$

Question 5

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

Accepted Answer

Compounds have properties that are generally different from the elements that compose them.

Question 6

Which of the following is NOT a correct statement about chemical formulas?

Accepted Answer

The order of elements in a chemical formula is always alphabetical.

Question 7

How many oxygen atoms are present in one formula unit of $$\mathrm{Mg(NO_3$)_2}$$?

Accepted Answer

6

Question 8

Which of the following is an empirical formula?

Accepted Answer

$$\mathrm{HO}$$

Question 9

Which model best represents the actual space occupied by atoms in a molecule?

Accepted Answer

Space-filling model

Question 10

Which of the following is a molecular element?

Accepted Answer

$$\mathrm{O_2$}$$

Question 11

Which of the following is an ionic compound?

Accepted Answer

$$\mathrm{NaCl}$$

Question 12

What is the correct formula for a compound formed from aluminum ions ($$\mathrm{Al$$^{3+}$$}) $$and oxide ions ($$\mathrm{O$$^{2-}$$}$$)?

Accepted Answer

$$\mathrm{Al_2O_3}$$

Question 13

Which of the following is true about mixtures and compounds?

Accepted Answer

Mixtures can have any proportions of their components, while compounds have fixed proportions.

Question 14

Which of the following is the correct chemical formula for carbon dioxide?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 15

If the subscript of oxygen in CO is changed from 1 to 2, what compound is formed?

Accepted Answer

Carbon dioxide

Question 16

Which rule is used to determine the order of elements in a chemical formula?

Accepted Answer

The most metallic element is listed first.

Question 17

How many nitrogen atoms are present in one formula unit of $$\mathrm{Mg(NO_3$)_2}$$?

Accepted Answer

2

Question 18

Which of the following is a correct molecular formula and its corresponding empirical formula?

Accepted Answer

Hydrogen peroxide: $$\mathrm{H_2O_2} ($$molecular), $$\mathrm{HO} ($$empirical)

Chapter 5: Molecules and Compounds – Study Notes

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