Q: A student measures the mass of a metal block as 45.0 g and its volume as 15.0 mL. What is the density of the metal?

$$\text{Density} = \frac{45.0\ \text{g}}{15.0\ \text{mL}} = 3.0\ \text{g/mL}$$

Q: The average atomic mass of chlorine is 35.45 u. If chlorine consists of two isotopes, $$^{35}Cl ($$mass = 34.97 u, abundance = 75.8%) and $$^{37}Cl ($$mass = 36.97 u, abundance = 24.2%), which equation correctly calculates the average atomic mass?

$$\text{Average atomic mass} = (34.97 \times 0.758) + (36.97 \times 0.242)$$

Q: A sample of a compound contains 24 g of magnesium and 16 g of oxygen. What is the mass percent of magnesium in the compound?

$$\frac{24}{24+16} \times 100 = 60\%$$

Question 1

Which of the following best describes the Law of Multiple Proportions?

Accepted Answer

When two elements form more than one compound, the ratio of the masses of the second element that combine with 1g of the first element can always be reduced to a small whole number.

Question 2

A sample of CO contains 12 g of carbon and 16 g of oxygen. A sample of CO$$_2$$ contains 12 g of carbon and 32 g of oxygen. According to the Law of Multiple Proportions, what is the ratio of the masses of oxygen that combine with 12 g of carbon in these two compounds?

Accepted Answer

$$\frac{32}{16} = 2$$

Question 3

Which of the following is the correct formula to convert a temperature from Celsius to Kelvin?

Accepted Answer

$$K = 273 + ^\circ C$$

Question 4

A student measures the mass of a metal block as 45.0 g and its volume as 15.0 mL. What is the density of the metal?

Accepted Answer

$$	ext{Density} = \frac{45.0\ 	ext{g}}{15.0\ 	ext{mL}} = 3.0\ 	ext{g/mL}$$

Question 5

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 6

The average atomic mass of chlorine is 35.45 u. If chlorine consists of two isotopes, $$^{35}Cl ($$mass = 34.97 u, abundance = 75.8%) and $$^{37}Cl ($$mass = 36.97 u, abundance = 24.2%), which equation correctly calculates the average atomic mass?

Accepted Answer

$$	ext{Average atomic mass} = (34.97 	imes 0.758) + (36.97 	imes 0.242)$$

Question 7

Which of the following is the correct name for the compound FeCl$$_3$$?

Accepted Answer

Iron(III) chloride

Question 8

Which of the following compounds is a molecular (covalent) compound?

Accepted Answer

CO$$_2$$

Question 9

What is the empirical formula for a compound with the molecular formula C$$_6H$_{12}O$_6$$?

Accepted Answer

CH$$_2O$$

Question 10

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

CH$$_2O$$

Question 11

Which of the following is the correct formula for the ionic compound formed between magnesium and nitrogen?

Accepted Answer

Mg$$_3N$_2$$

Question 12

Which of the following best describes a cation?

Accepted Answer

A positively charged ion formed by the loss of electrons

Question 13

What is the correct name for the compound N$$_2O$_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 14

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

Ca$$_3(PO$_4$$)$$_2$$

Question 15

A sample of a compound contains 24 g of magnesium and 16 g of oxygen. What is the mass percent of magnesium in the compound?

Accepted Answer

$$\frac{24}{24+16} 	imes 100 = 60\%$$

Question 16

Which of the following is the correct name for H$$_2SO$_4$$?

Accepted Answer

Sulfuric acid

Question 17

Which of the following is the correct formula for dinitrogen trioxide?

Accepted Answer

N$$_2O$_3$$

Question 18

A patient’s body temperature is measured as 102.2 $$^\circF. $$What is this temperature in Celsius?

Accepted Answer

$$\frac{5}{9}(102.2 - 32) = 39.0\ ^\circ C$$

Question 19

Which of the following is the correct name for the compound NaOH?

Accepted Answer

Sodium hydroxide

Question 20

Which of the following is the correct molecular formula for a compound with 2 hydrogen atoms and 2 oxygen atoms?

Accepted Answer

H$$_2O$_2$$

Fundamental Concepts in General Chemistry: Units, Atomic Structure, and Chemical Compounds

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