Question

exam lesson name: states of matter
exam number: 700698rr
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▶ exam instructions

question 20 of 20 :
select the best answer for the question.

1. the density difference between warm, moist air and cold air causes the moist air to rise. this is key to forming

○ a. lightning.
○ b. clouds.
○ c. stars.
○ d. snow.

□ mark for review (will be highlighted on the review page)

Explanation:

To solve this, we analyze each option:

• Option A: Lightning is an electrical discharge, not directly related to air density - driven rising of moist air.
• Option B: Clouds form when warm, moist air rises (due to lower density than cold air), cools, and water vapor condenses. This matches the described process.
• Option C: Stars form from cosmic gas/dust collapse, unrelated to air density differences on Earth.
• Option D: Snow is precipitation, but the rising moist air first forms clouds (which can then produce snow), so the key initial formation here is clouds.

Answer:

B. clouds.