Which of the following could provide defective evidence of a chemical change choose two correct answers
A new substance rust has formed
A solid has dissolved in a liquid
Liquid water has frozen to form ice
A new substance oxygen gas has formed
Two correct answers are:
1. A solid has dissolved in a liquid: This is not evidence of a chemical change, but rather a physical change. The original substances are still present, just in a different state (solid dissolved in liquid).
2. Liquid water has frozen to form ice: This is also not evidence of a chemical change. Freezing is a physical change where water molecules rearrange themselves to form a solid, but the chemical composition of water remains the same.
The two correct answers are:
1. A solid has dissolved in a liquid
2. Liquid water has frozen to form ice