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Here are some multiple-choice questions based on the provided information:

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1. What does the boiling point of a liquid refer to?

a) The temperature at which a solid becomes a liquid

b) The temperature at which the vapor pressure of a liquid equals the external or atmospheric pressure

c) The temperature at which a liquid becomes a solid

d) The temperature at which a gas becomes a liquid

Answer: b) The temperature at which the vapor pressure of a liquid equals the external or atmospheric pressure

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2. What happens during the boiling process of a liquid?

a) The liquid absorbs energy and forms solid crystals

b) Bubbles of vapor form only on the surface of the liquid

c) Bubbles of vapor form throughout the liquid and rise to the surface

d) The liquid temperature continuously increases as it boils

Answer: c) Bubbles of vapor form throughout the liquid and rise to the surface

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3. How does atmospheric pressure affect the boiling point of a liquid?

a) A liquid will boil at the same temperature regardless of pressure

b) A higher external pressure increases the boiling point

c) A lower external pressure increases the boiling point

d) Atmospheric pressure has no effect on boiling point

Answer: b) A higher external pressure increases the boiling point

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4. What is the normal boiling point of a liquid?

a) The temperature at which the liquid's vapor pressure is zero

b) The temperature at which the liquid’s vapor pressure equals 1 atm (760 mmHg)

c) The temperature at which a liquid freezes

d) The temperature at which the liquid’s vapor pressure equals 2 atm

Answer: b) The temperature at which the liquid’s vapor pressure equals 1 atm (760 mmHg)

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5. What happens to a liquid during condensation?

a) The liquid absorbs energy and turns into gas

b) The gas releases energy and turns into liquid

c) The gas absorbs energy and remains in gaseous form

d) The liquid freezes into a solid

Answer: b) The gas releases energy and turns into liquid

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6. Which of the following statements about the boiling points of pure substances and mixtures is correct?

a) Pure substances have broad boiling ranges, while mixtures have sharp boiling points

b) Mixtures have sharp boiling points, while pure substances have broad boiling ranges

c) Pure substances have characteristic sharp boiling points, while mixtures have broad boiling ranges

d) Both pure substances and mixtures have sharp boiling points

Answer: c) Pure substances have characteristic sharp boiling points, while mixtures have broad boiling ranges

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7. At what temperature does pure water boil at 1 atm?

a) 78.5°C

b) 34.6°C

c) 100°C

d) 0°C

Answer: c) 100°C

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8. Which factor directly affects the boiling point of a substance?

a) The amount of liquid

b) The molecular structure and intermolecular forces of the substance

c) The volume of the container

d) The color of the liquid

Answer: b) The molecular structure and intermolecular forces of the substance