Question 1

Which of the following best explains why sodium chloride (NaCl) has properties very different from both elemental sodium and elemental chlorine?

Accepted Answer

Because NaCl is a compound, and compounds have properties that are generally different from the elements that compose them.

Question 2

Which statement correctly distinguishes a compound from a mixture?

Accepted Answer

A compound is made of elements combined in fixed, definite proportions, while a mixture can have variable proportions.

Question 3

A sample of water is decomposed and found to contain 16.0 g of oxygen and 2.0 g of hydrogen. What is the mass ratio of oxygen to hydrogen in water?

Accepted Answer

$$\frac{16.0\ g\ O}{2.0\ g\ H} = 8.0$$

Question 4

Which law states that all samples of a given compound have the same proportions of their constituent elements?

Accepted Answer

Law of Constant Composition (Definite Proportions)

Question 5

Given two samples of dinitrogen monoxide ($$N_2O$$): Sample 1 contains 9.866 g N and 5.634 g O; Sample 2 contains 16.23 g N and 9.269 g O. Are these consistent with the law of constant composition? Calculate the mass ratio for both samples.

Accepted Answer

Yes, because $$\frac{9.866}{5.634} = 1.751$$ and $$\frac{16.23}{9.269} = 1.751$$, which are the same.

Question 6

Which of the following is the correct chemical formula for a compound containing one magnesium atom, two chlorine atoms, and six oxygen atoms?

Accepted Answer

$$\mathrm{Mg($$ClO_3$$)_2}$$

Question 7

Which of the following is an example of a molecular element?

Accepted Answer

Nitrogen ($$N_2)$$

Question 8

What is the empirical formula for hydrogen peroxide ($$H_2O_2$$)?

Accepted Answer

$$HO$$

Question 9

Which of the following best describes a structural formula?

Accepted Answer

It uses lines to represent chemical bonds and shows how atoms are connected in a molecule.

Question 10

Which of the following is a correct classification for $$SO_2$$?

Accepted Answer

Molecular compound

Question 11

Which of the following is a polyatomic ion?

Accepted Answer

$$NO_3$$^-$$

Question 12

Which of the following statements about chemical formulas is correct?

Accepted Answer

Changing a subscript in a chemical formula creates a different compound.

Question 13

Which of the following is the correct order for listing elements in a chemical formula?

Accepted Answer

List the most metallic element first.

Question 14

Which of the following is an example of an ionic compound?

Accepted Answer

$$Na_2O$$

Question 15

How many total oxygen atoms are present in one formula unit of $$Fe_2$$($$SO_4)_3$?

Accepted Answer

12

Question 16

Which of the following best describes a molecular model?

Accepted Answer

A three-dimensional representation that shows the arrangement of atoms and bonds in a molecule.

Question 17

Which of the following is a molecular compound?

Accepted Answer

$$NO$$

Question 18

Which of the following is a diatomic molecular element?

Accepted Answer

$$Cl_2$$

Question 19

Which of the following is the empirical formula for oxalic acid ($$C_2H_2O_4$$)?

Accepted Answer

$$CHO_2$$

Question 20

Which of the following best describes the basic unit of an ionic compound?

Accepted Answer

Formula unit

Study Notes: Molecules and Compounds (General Chemistry, Chapter 5)

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