Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Sulfate minerals contain sulfur atoms bonded to oxygen atoms. Like halides, they can form in places where salt water evaporates. Many minerals belong in the sulfate group, but there are only a few common sulfate minerals. Gypsum is a common sulfate mineral that contains calcium, sulfate, and water. Gypsum is found in various forms. For example, it can be pink and look like it has flower petals. However, it can also grow into very large white crystals. Gypsum crystals that are 11 meters long have been found. That is about as long as a school bus! Gypsum also forms at the Mammoth Hot Springs in Yellowstone National Park, shown in Figure below . Answer: oxygen and sulfur

Answer: What two types of atoms bond to form sulfate minerals?

Question: Passage: Oxygen is needed to make ozone. Ozone is a molecule made of three oxygen ions. Ozone in the upper atmosphere blocks harmful solar radiation from reaching the surface. Without oxygen, life on Earth would have been very simple. Answer: three

Answer: How many oxygen ions make up an ozone molecule?

Question: Passage: Capillaries are the smallest type of blood vessels. They connect the smallest arteries (arterioles) and veins (venules). Exchange of substances between cells and the blood takes place across the walls of capillaries, which may be only one cell thick. Answer: capillaries

Answer:
What is the term for the smallest blood vessels?