Within group 1, the reactivity of the alkali metals increases from top to bottom.
Correct Answer
True
True. Atomic radius increases down the group, so the single valence electron is held less tightly and lost more easily, making cesium far more reactive than lithium.
Category: Periodic Trends
Question 2
In group 12, mercury is the most reactive metal and zinc is the least reactive.
Correct Answer
False
False. In group 12 the trend runs the opposite way from groups 1 and 2: zinc is the most reactive and mercury the least.
Category: Periodic Trends
Question 3
Silicon for computer chips is purified by zone refining until very few impurity atoms remain.
Correct Answer
True
True. Impure silicon is converted to a volatile compound, decomposed back to silicon, and then zone refined, leaving an extremely low level of impurities suitable for semiconductors.
Category: Metalloids
Question 4
Boron makes up nearly one quarter of Earth's crust by mass.
Correct Answer
False
False. Silicon makes up nearly one quarter of the crust. Boron is rare, making up less than 0.001% of the crust, and occurs only combined with oxygen.
Category: Metalloids
Question 5
Deuterium is an isotope of hydrogen whose nucleus contains one proton and one neutron.
Correct Answer
True
True. Deuterium has a mass number of 2 because its nucleus has one proton and one neutron. Ordinary hydrogen has no neutron, and tritium has two.
Category: Hydrogen
Question 6
In ionic hydrides such as CaH2, hydrogen has an oxidation state of +1.
Correct Answer
False
False. In ionic hydrides hydrogen is present as the hydride ion, H-, with an oxidation state of -1. Hydrogen is +1 in compounds with nonmetals such as HCl.
Category: Hydrogen
Question 7
Calcium carbonate dissolves in water that contains dissolved carbon dioxide, forming soluble calcium hydrogen carbonate.
Correct Answer
True
True. This reaction slowly dissolves limestone to form caves and sinkholes, and when the water later evaporates, calcium carbonate is deposited again as stalactites and stalagmites.
Category: Carbonates
Question 8
Baking soda is the compound sodium carbonate.
Correct Answer
False
False. Baking soda is sodium hydrogen carbonate, NaHCO3. It releases carbon dioxide when it reacts with an acid, which makes dough rise.
Category: Carbonates
Question 9
Metal carbonates react with acids to produce a salt, water, and carbon dioxide gas.
Correct Answer
True
True. The H+ ions of the acid convert carbonate ions into carbonic acid, which breaks down to water and carbon dioxide. This is how a calcium carbonate antacid neutralizes stomach acid.
Category: Carbonates
Question 10
Red phosphorus is more reactive and more toxic than white phosphorus.
Correct Answer
False
False. White phosphorus is the more reactive and toxic form and ignites in air. Red phosphorus, a polymer of linked P4 units, is much less reactive and essentially nontoxic.
Category: Nitrogen and Phosphorus
Question 11
Phosphorus(V) oxide, P4O10, is useful as a drying agent because it reacts readily with water.
Correct Answer
True
True. P4O10 has a strong attraction for water and reacts with it to form phosphoric acid, H3PO4, so it efficiently removes moisture from gases and liquids.
Category: Nitrogen and Phosphorus
Question 12
The oxidation states of nitrogen in its compounds range from -3 to +3.
Correct Answer
False
False. Nitrogen's oxidation states range from -3, as in ammonia, to +5, as in nitric acid and the nitrate ion.
Category: Nitrogen and Phosphorus
Question 13
Rhombic sulfur, the stable form at room temperature, is made of rings of eight sulfur atoms.
Correct Answer
True
True. Rhombic sulfur consists of crown-shaped S8 rings. Sulfur has more allotropes than any other element.
Category: Oxygen and Sulfur
Question 14
Ozone forms from O2 in an exothermic reaction.
Correct Answer
False
False. Forming ozone from O2 is endothermic, so it requires an energy input such as an electric discharge, heat, or ultraviolet light.
Category: Oxygen and Sulfur
Question 15
The peroxide ion, O2 2-, contains an oxygen-oxygen single bond.
Correct Answer
True
True. Each oxygen in the peroxide ion has an oxidation state of -1, and the two atoms are joined by a single bond. Hydrogen peroxide, H2O2, contains the same O-O single bond.
Category: Oxygen and Sulfur
Question 16
Nonmetal oxides such as SO3 react with water to form bases.
Correct Answer
False
False. Nonmetal oxides are acidic oxides: SO3 reacts with water to form sulfuric acid. Metal oxides such as CaO are the ones that form bases.
Category: Oxygen and Sulfur
Question 17
Iodine is a solid at room temperature that sublimes to a violet vapor.
Correct Answer
True
True. Iodine forms grayish-black crystals that pass directly into a deep violet vapor when warmed. It is the only common halogen that is a solid at room temperature.
Category: Halogens and Noble Gases
Question 18
Bromine is produced commercially by oxidizing bromide ions with fluorine.
Correct Answer
False
False. Bromine is produced by oxidizing bromide ions with chlorine, which is a stronger oxidizing agent than bromine: 2Br- + Cl2 -> Br2 + 2Cl-.
Category: Halogens and Noble Gases
Question 19
Xenon forms stable compounds with fluorine, such as XeF2.
Correct Answer
True
True. Although the noble gases were once thought to be unreactive, xenon forms stable fluorides including XeF2, XeF4 and XeF6.
Category: Halogens and Noble Gases
Question 20
Helium is obtained commercially by the fractional distillation of liquid air.
Correct Answer
False
False. Helium is obtained from certain natural gas deposits that contain small percentages of it. Neon, argon, krypton and xenon are the noble gases recovered from liquid air.
Category: Halogens and Noble Gases