Q: A naturally occurring sample of an element contains two isotopes: 70% $$^{35}\mathrm{Cl} ($$mass = 34.97 u) and 30% $$^{37}\mathrm{Cl} ($$mass = 36.97 u). What is the average atomic mass of chlorine?

$$(0.70 \times 34.97) + (0.30 \times 36.97) = 35.57 u$$

Question 1

Which of the following statements about atoms is FALSE?

Accepted Answer

Atoms can be divided into smaller particles by ordinary chemical means.

Question 2

A sample of sodium fluoride (NaF) is used in toothpaste to prevent tooth decay. Which type of compound is NaF?

Accepted Answer

Ionic compound

Question 3

How many neutrons are present in $$^{14}_{6}\mathrm{C}$$?

Accepted Answer

8

Question 4

An atom contains 16 protons, 18 neutrons, and 16 electrons. What is the correct symbol for this isotope?

Accepted Answer

$$^{34}_{16}\mathrm{S}$$

Question 5

Which of the following best describes a cation?

Accepted Answer

An atom that has lost electrons and is positively charged.

Question 6

Which group of elements in the periodic table is also called the alkaline earth metals?

Accepted Answer

Group 2

Question 7

A phosphorus ion with 18 electrons is most likely to have which of the following charges?

Accepted Answer

$$3-$$

Question 8

Which of the following statements about isotopes is TRUE?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 9

How many oxygen atoms are in the formula $$\mathrm{Al}_2(\mathrm{SO}_4)_3$$?

Accepted Answer

12

Question 10

Which of the following best explains why sodium nitrate (NaNO$$_3) is $$used in medical applications?

Accepted Answer

It is an antifungal and antihypertensive agent.

Question 11

Which of the following is the correct formula for the ionic compound made of magnesium and selenium?

Accepted Answer

MgSe

Question 12

How many of each type of atom are there in the formula $$(\mathrm{NH}_4)_3\mathrm{PO}_4$$?

Accepted Answer

N = 3, H = 12, P = 1, O = 4

Question 13

Which of the following best describes the difference between metals and nonmetals in the periodic table?

Accepted Answer

Metals tend to lose electrons in chemical changes, while nonmetals tend to gain electrons.

Question 14

Which of the following is the correct name for the ionic compound made of beryllium and chlorine?

Accepted Answer

Beryllium chloride

Question 15

A naturally occurring sample of an element contains two isotopes: 70% $$^{35}\mathrm{Cl} ($$mass = 34.97 u) and 30% $$^{37}\mathrm{Cl} ($$mass = 36.97 u). What is the average atomic mass of chlorine?

Accepted Answer

$$(0.70 	imes 34.97) + (0.30 	imes 36.97) = 35.57 u$$

Question 16

Which of the following best describes the relationship between protons, neutrons, and electrons in a neutral atom?

Accepted Answer

The number of protons equals the number of electrons.

Question 17

Which of the following is the correct formula for barium carbonate?

Accepted Answer

BaCO$$_3$$

Question 18

Which of the following statements about ions is TRUE?

Accepted Answer

Cations and anions occur together so that matter is charge neutral.

Question 19

A sample contains an atom with 8 protons, 8 neutrons, and 7 electrons. What is the charge of this atom?

Accepted Answer

$$+1$$

Question 20

Which of the following best describes the periodic table?

Accepted Answer

It arranges elements in order of increasing atomic number.

Atoms, Elements, Molecules, and Compounds: Foundations of Chemistry

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