You are interested in determining the amount of citric acid present in a sample of 7-Up. Will your results be different if you use a sample that has been open for an hour instead of a freshly opened bottle? Explain.

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

indium, and thallium have three electrons i think

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

elements make up everything, and they combine to make compounds.

the answer is c