Practice Quiz

MCAS Biology Practice - Question List

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241. Which of the following explains why saltwater is considered a mixture?
  1. It is composed of one element.
  2. It is composed of one compound.
  3. It is composed of two or more substances and has new
    chemical properties.
  4. It is composed of two or more substances that retain their own chemical properties.
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242. When stirred in 30°C water, 5 g of powdered potassium bromide, KBr, dissolves faster than 5 g of large crystals of potassium bromide. Which of the following best explains why the powdered KBr dissolves faster?
  1. Powdered potassium bromide exposes more surface area to water molecules than large crystals of potassium bromide.
  2. Potassium ions and bromide ions in the powder are smaller than potassium ions and bromide ions in the large crystals.
  3. Fewer potassium ions and bromide ions have been separated from each other in the powder than in the crystals.
  4. Powdered potassium bromide is less dense than large crystals of potassium bromide.
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243. Which of the following is an example of a physical change?
  1. Iron exposed to air produces rust.
  2. Hydrogen combined with oxygen forms water.
  3. Sulfur combined with oxygen produces sulfur dioxide.
  4. Liquid nitrogen exposed to air becomes nitrogen gas.
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244. Which of the following trends in the periodic table should be expected as the atomic number of the halogens increases from fluorine (F) to iodine (I)?
  1. Atomic radius decreases.
  2. Electronegativity decreases.
  3. Atomic mass decreases.
  4. Electron number decreases.
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245. Which of the following statements describes the elements in family 16 of the periodic table?
  1. They have six valence electrons.
  2. They are all gases at room temperature.
  3. They exist commonly as cations in nature.
  4. They combine easily with elements in family 17.
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