MCAS Biology Practice - Question List

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211. Which of the following statements best explains why water vapor condenses as temperature decreases?
  1. Collisions between water vapor molecules become elastic.
  2. Water vapor molecules chemically react when they collide.
  3. Water vapor molecules are pulled together by the force of gravity.
  4. Attractive forces between water vapor molecules overcome molecular motion.
212. Which of the following elements is a member of the halogen family and is located in period 3?
  1. argon (Ar)
  2. bromine (Br)
  3. chlorine (Cl)
  4. sulfur (S)
213. Which of the following statements describes a difference between a mixture and a pure substance?
  1. A mixture tends to be homogenous, while a pure substance tends to be heterogeneous.
  2. A mixture has a specific melting point, while the melting point
    of a pure substance can vary.
  3. The density of a mixture can change with temperature, but the density of a pure substance cannot change.
  4. The composition of a mixture can vary from sample to sample, but the composition of a pure substance is always the same.
214. Which of the following pieces of evidence best supports Bohr’s idea that electrons occupy specific energy levels within an atom?
  1. Sodium atoms become positive ions when they lose electrons.
  2. Each element emits a unique brightline spectrum when it falls from an excited state to a ground state.
  3. Beryllium atoms bombarded with alpha particles produce beams that are not influenced by magnetic fields.
  4. Each element has physical and chemical properties that are unique to that element and different from those of other elements.
215. The air inside a beach ball is at a temperature of 25°C and a pressure of 1.0 atm. If the ball contains 0.85 mol of air, what is its volume?
  1. 1.7 L
  2. 6.1 L
  3. 21 L
  4. 27 L

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