*Question*
Q: What process does water undergo to leave behind dissolved substances? Read this paragraph and choose the correct option from the provided answers: Minerals form from dissolved substances when water evaporates. Choices: - accumulation - oxidation - ascension - evaporation A:
**Answer**
evaporation

*Question*
Q: What is a mixture of potassium nitrate, sulfur, and charcoal? Read this paragraph and choose the correct option from the provided answers: Nitrates, salts of nitric acid, form when metals, oxides, hydroxides, or carbonates react with nitric acid. Most nitrates are soluble in water; indeed, one of the significant uses of nitric acid is to prepare soluble metal nitrates. Nitric acid finds extensive use in the laboratory and in chemical industries as a strong acid and strong oxidizing agent. It is important in the manufacture of explosives, dyes, plastics, and drugs. Salts of nitric acid (nitrates) are valuable as fertilizers. Gunpowder is a mixture of potassium nitrate, sulfur, and charcoal. The reaction of N2O3 with water gives a pale blue solution of nitrous acid, HNO2. However, HNO2 (shown in Figure 18.51) is easier to prepare by the addition of an acid to a solution of nitrite; nitrous acid is a weak acid, so the nitrite ion is basic in aqueous solution: NO 2 (aq) + H 3 O +(aq) HNO 2(aq) + H 2 O(l) Nitrous acid is very unstable and exists only in solution. It disproportionates slowly at room temperature (rapidly when heated) into nitric acid and nitric oxide. Nitrous acid is an active oxidizing agent with strong reducing agents, and strong oxidizing agents oxidize it to nitric acid. Choices: - gasoline - cyanide - TNT - gunpowder A:
**Answer**
gunpowder

*Question*
Q: About how full is the outer energy level in metalloids? Read this paragraph and choose the correct option from the provided answers: Metalloids such as boron have an outer energy level that is about half full. These elements need to gain or lose too many electrons for a full outer energy level to come about easily. As a result, these elements are not very reactive. They may be able to conduct electricity but not very well. Choices: - nearly empty - three-fourth full - a quarter full - half full A:
**Answer**
half full

*Question*
Q: Particles of sand and what other substance are carried by longshore drift? Read this paragraph and choose the correct option from the provided answers: Longshore drift carries particles of sand and rock down a coastline. Choices: - magma - bone - soil - rock A:
**Answer**
rock