# E-PolyLearning

 1. Ordinary table salt is sodium chloride. What is baking soda? a. Potassium chloride b. Potassium carbonate c. Potassium hydroxide d. Sodium bicarbonate

 2. Ozone hole refers to a. hole in ozone layer b. decrease in the ozone layer in troposphere c. decrease in thickness of ozone layer in stratosphere d. increase in the thickness of ozone layer in troposphere