“It can hold two electrons”
I believe the answer is D. The atmosphere, different layers of the atmosphere can help in different ways! The stratosphere helps protect us from the sun's rays; The Mesophere is what helps protect us from meteorites! It's so cold that they burn up in that area.
Procedures that are likely a chemical change are:
- Bubbles were produced when iron was placed in acid.
- Two liquids were combined, and a solid appeared
- A white substance turned blue when water was added.