LET360 owl LET360

Science Chemistry — LET Practice Questions

This Science Chemistry section of the LET General Education exam covers 7 expert-reviewed practice questions. Each question has a plain-English explanation and notes on why the wrong answers are wrong.

7 reviewed questions on Science Chemistry — and over 300 across General Education overall — are available with a free LET360 account. Sign up free →

Sample questions with answers and explanations

Sample 1

Which of the following demonstrate sublimation?

Answer: A

Sublimation is when a SOLID turns directly into a GAS, skipping the liquid phase. Dry ice (frozen CO2) doesn't melt into a puddle — it goes straight to gas (that's why it 'smokes'). Other examples: mothballs, snow disappearing on a freezing day without melting.

Tip: Sublimation requires SOLID → GAS, no liquid in between. Dry ice is the classic example.

Why the other choices are wrong
  • B. Perspiration is liquid sweat → gas. That's evaporation, not sublimation.
  • C. Wet laundry (liquid water) → dry (water vapor). That's evaporation, not sublimation.
  • D. Steam (gas) → water droplets (liquid). That's condensation — opposite direction.

Sample 2

The following describe chemical change except

Answer: A

A physical change just changes how something looks (like melting ice into water—it's still water). A chemical change creates a brand new substance (like burning wood into ash). Melting is physical, not chemical.

Test-Taker Tip: If you can easily reverse it (like freezing the melted liquid back into a solid), it's a Physical change.

Why the other choices are wrong
  • B. Producing heat, light, or gas is a CLASSIC sign of chemical change.
  • C. Souring milk forms new substances (lactic acid) — that's chemical change.
  • D. Forming a new substance is the very definition of chemical change.

Sample 3

Copper is used for electrical wires because it is ductile. Which of the following describes ductility of metals?

Answer: C

Ductility = the ability to be drawn (stretched) into thin wires. Copper is super ductile, which is why electrical wires are made from it. Don't confuse with malleability (ability to be hammered into sheets — like aluminum foil).

Tip: Ductile = wires (Drawn). Malleable = sheets (Mashed/Mallet). Different but related properties.

Why the other choices are wrong
  • A. Softness ≠ ductility. Lead is soft but not as ductile as copper.
  • B. Hardness is the opposite — hard metals are usually less ductile.
  • D. That's MALLEABILITY (hammered into sheets), not ductility.
Want all 7 questions on Science Chemistry plus timed practice tests?
Sign up free with Google →

Related topics