2H2+O2→2H2O There are four atoms of hydrogen (H) before the reaction. How many atoms of hydrogen are present after the reaction?

4

8

5

2

Which of the following mining methods disrupts the sea floor?

When you perform this reaction, what could remain at the end of the reaction? check all that apply. excess reactant aqueous copper chloride excess reactant aluminum oxygen product solid copper carbon dioxide product aqueous aluminum chloride water

The human activities in two locations are described below: location a: rampant use of plastic containers location b: excessive use of pesticides and fertilizers which statement is most likely true? location a will have poor air quality because plastic is biodegradable. location a will experience water scarcity because plastic absorbs moisture. the population of honeybees will increase in location b because production of crops will increase. the population of fish in location b will decrease because the water is contaminated.