1. In the reaction C5H8 + ______ O2 --> 8H2O + 5CO2, what coefficient should be placed in front of O2 to balance the reaction?
   

A5

B8

C9

Dno coefficient is needed

1. How does the law of conservation of mass apply to this reaction: C2H4 + O2 --> 2H2O + 2CO2?
   
   

AEach element needs to be balanced.

BThe equation needs to be balanced. There are fewer oxygen atons in the equation than hydrogen or carbon.

COnly the oxygen needs to be balanced. There are equal numbers of hydrogen and carbon.

DThe law of conservation of mass has already been applied. There is an equal number of each element on both sides of the equation

1. How does the law of conservation of mass apply to this reaction: Mg + HCl --> H2 + MgCl2?
   
   

AThe law of conservation of mass has already been applied. There is an equal number of each element on both sides of the equation.

BOnly the hydrogen needs to be balanced. There are equal amount of magnesium and chlorine.

CHydrogen and chlorine need to be balanced. There is an equal amount of magnesium on each side.

DThe equation needs to be balanced. There are a few hydrogen atoms in the equation than magnesium or chlorine.

1. Which of these is an example of a solution?
   
   

Aoil and vinegar in a salad dressing jar

Ba glass of water with ice in it

Csugar stirred in tea

Dsand stirred in water