Question 1

Which of the following statements best illustrates the law of constant composition?

Accepted Answer

All pure samples of water, regardless of their source, have a mass ratio of oxygen to hydrogen of $8:1$.

Question 2

Which of the following is the correct empirical formula for hydrogen peroxide, whose molecular formula is $H_2O_2$?

Accepted Answer

$HO$

Question 3

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

Accepted Answer

$Al_2O_3$

Question 4

Which of the following compounds is classified as a molecular compound?

Accepted Answer

Carbon dioxide ($CO_2$)

Question 5

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

Accepted Answer

6

Question 6

Which of the following is the correct name for $FeCl_3$?

Accepted Answer

Iron(III) chloride

Question 7

What is the correct formula for calcium phosphate, given that the phosphate ion is $PO_4^{3-}$ and the calcium ion is $Ca^{2+}$?

Accepted Answer

$Ca_3(PO_4)_2$

Question 8

Which of the following is the correct name for $N_2O_5$?

Accepted Answer

Dinitrogen pentoxide

Question 9

A sample of ammonia ($NH_3$) is decomposed and found to contain 14.0 g of nitrogen and 3.0 g of hydrogen. What is the mass ratio of nitrogen to hydrogen in ammonia?

Accepted Answer

$4.7:1$

Question 10

Which of the following is the correct name for $H_2SO_4$ (aq)?

Accepted Answer

Sulfuric acid

Question 11

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

Accepted Answer

Nitrogen

Question 12

What is the formula mass of sodium carbonate ($Na_2CO_3$)? (Atomic masses: $Na = 23.0$, $C = 12.0$, $O = 16.0$)

Accepted Answer

$106.0$ g/mol

Question 13

Which of the following is the correct name for $KNO_2$?

Accepted Answer

Potassium nitrite

Question 14

Which of the following is a correct statement about ionic compounds?

Accepted Answer

They are composed of cations and anions in a three-dimensional array.

Question 15

What is the correct name for $HClO_3$ (aq)?

Accepted Answer

Chloric acid

Question 16

Which of the following formulas represents a compound containing both a polyatomic cation and a polyatomic anion?

Accepted Answer

$NH_4NO_3$

Question 17

Which of the following is the correct name for $CuSO_4$?

Accepted Answer

Copper(II) sulfate

Question 18

Which of the following is the correct formula for iron(III) hydroxide?

Accepted Answer

$Fe(OH)_3$

Question 19

Which of the following is the correct name for $P_2O_5$?

Accepted Answer

Diphosphorus pentoxide

Question 20

A student is given a white powder and told it is either sodium chloride ($NaCl$) or sucrose ($C_{12}H_{22}O_{11}$). Which of the following would best distinguish between the two at the molecular level?

Accepted Answer

Determine if the sample contains both sodium and chlorine atoms in a 1:1 ratio.

Molecules and Compounds: Structure, Classification, and Nomenclature

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