A student tested a sample of carbon (C) by combining it with water. There was no reaction between the carbon and water. The student concluded that carbon must be a
group 18 element, since it was unreactive is this conclusion correct? Why or why not?

A. Yes Water would react with almost every element, except Group 18 elements
B. No. The carbon probably did react, but did not give off any signs or indications of a chemical
change
C. No. Just because carbon did not react with water, does not mean it wouldn't react with a
different compound
D. Yes. The student can make a reasonable conclusion based on one experiment.

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

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

b.

the accuracy of the data.