Q: In order for a glider to fly, its weight must be opposed by ---- OPTIONS:
- lift.
- drag.
- gravity.
- friction.

A: lift.

Q: A layer of solid brittle rock comprises the outer 100 kilometers of Earth. This layer, which contains both the crust and the upper mantle, is called the ---- OPTIONS:
- core.
- sediment.
- lithosphere.
- hemisphere.

A: lithosphere.

Q: Which statement correctly describes why there are fewer than 24 hours of daylight in Alaska during each day in April? ---- OPTIONS:
- Earth's rotation slows during the day.
- Earth's rotation slows during the night.
- Earth's rotation causes both day and night.
- Earth's tilt on its axis causes both day and night.

A: Earth's rotation causes both day and night.

Q: A drain cleaner consists of sodium hydroxide and aluminum. When the drain cleaner is added to water, bubbles of hydrogen are produced, and the solution becomes very hot. Which of these best describes what happens to form the bubbles when the cleaner is added to water? F ---- OPTIONS:
- chemical reaction
- Condensation
- A physical change
- Evaporation
A: chemical reaction