To burn 1 molecule of c5h12 to form co2 and h2o (complete combustion), how many molecules of o2 are required?

8 molecules of oxygen gas are required.

Explanation:

Combustion reaction is the type of chemical reaction in which a hydrocarbon reacts with oxygen gas to give to carbon dioxide and water.

According to reaction ,1 mole of pentane reacts with 8 molecules of oxygen gas to give 5 moles of carbon dioxide and 6 moles of water.

So, to burn 1 mole of pentane we will need 8 molecules of oxygen gas.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e