Answer:
Demonstration 1 showed a chemical change because a new gaseous substance was formed, and demonstration 2 showed a physical change because liquid water became water vapor.
Explanation:
Chemical changes alter the chemical makeup of a subject, and a physical change only alters the appearance of a subject, not the chemical makeup.
Answer:
the citric acid in lemon juice is a natural bleach, or oxidizing agent. It whitens hair by chemically reducing your hair's color pigment, or melanin. When exposed to the sun, the citric acid accelerates the bleaching process
Answer:
The yeast present contains an enzyme called catalase which catalyses the reaction. More the amount of the catalyst added, faster will be the decomposition of the hydrogen peroxide.
C6H12O6 +6O2 —> 6CO2 + 6H2O