Question

Which of the following is not true about chemical changes? a. They form a new substance. b. They can be reversed by physical changes. c. They can be detected by changes such as color. d. They have different properties from their starting materials.

Answer 1

Answer: The correct option is b.

Explanation: Chemical reaction is a reaction i which the chemical composition of the reactants gets changed and new substances having different chemical composition is formed. This reaction cannot be reversed by any physical means.

Indicators showing chemical changes are :

• Color change
• Characteristic odor
• Formation of bubbles
• Formation of precipitate

From the given information above, it can be stated that the correct option is b.

Answer 2

The following that is not true about chemical changes is "They can be reversed by physical changes.", the answer is letter B. A chemical change can form a new substance, can be detected by the change in color and they have properties different from their starting materials.