Answer:
The answer is A
Explanation:
It is logical because the balloon lets the student see how much gas is released in the reaction. the balloon inflates with invisible air the student will normally not see.
Answer:
pollution of water. or do you mean pollutant in which case would be like garbage or oil spills
Cells don't grow very big because they have to be able to diffuse through material easily. Also, when cells are small and plentiful they are easy to replace when damaged.
Injecting.
smoking.
inhaling.
snorting.
swallowing.
Fatigue can have causes that aren't due to underlying disease. Examples include lack of sleep, heavy exertion, jetlag, a large meal, or aging.