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Science Earth Science — LET Practice Questions

This Science Earth Science section of the LET General Education exam covers 5 expert-reviewed practice questions. Each question has a plain-English explanation and notes on why the wrong answers are wrong.

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Sample questions with answers and explanations

Sample 1

Which of the following best describes the mantle?

Answer: A

The Earth has 4 layers from the inside out: inner core, outer core, MANTLE, and crust. The mantle is the BIGGEST layer — about 2,900 km thick — making up roughly 84% of Earth's volume. It's hot, semi-solid rock that slowly flows.

Tip: For 'best describes' Earth-science layer questions, look for the option that names a defining feature (size, location, composition) — not a process or a different concept entirely.

Why the other choices are wrong
  • B. That's 'subduction' — when one tectonic plate slides under another. Different concept.
  • C. That's the atmosphere — the air around Earth, not a layer inside it.
  • D. That describes the rock cycle — how rocks form and change. Not the mantle.

Sample 2

A town that is located ______ is a location that should have most nearly twelve hours of daylight and twelve hours of darkness during December.

Answer: B

Because the Earth is tilted, the North and South poles have crazy daylight hours in the winter and summer. But the Equator is right in the middle of the planet, so it always gets a perfectly even split: 12 hours of light and 12 hours of dark, all year round.

Test-Taker Tip: 12 hours light / 12 hours dark = The Equator.

Why the other choices are wrong
  • A. Halfway to the South Pole means the day length varies a lot in December.
  • C. Near the North Pole in December, daylight is very short (or zero), not 12 hours.
  • D. Near the South Pole in December (summer there), daylight is very long, not 12 hours.

Sample 3

Two air masses have the same relative humidity. Which of the following can also be said about them?

Answer: D

Relative humidity is just a percentage of how 'full' the air is with water. A cold room and a hot room can both be 50% full (same relative humidity), even though the hot room holds way more actual water. So, you can't assume they have the same temperature, volume, or clouds.

Test-Taker Tip: Relative humidity is just a percentage (%), not an absolute amount.

Why the other choices are wrong
  • A. Same humidity percentage doesn't mean same volume — the air masses can be any size.
  • B. Same percentage doesn't mean same temperature — cold and hot air can both be 50% full.
  • C. Rain clouds form only at 100% humidity (saturation), not at every same percentage.
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