Question

5. Predict Suppose you have found an

unknown substance in a laboratory. It has
the formula H₂O, written on the bottle. Is it
water? How do you know?

Answer 1

Yes, it contains water because H2O is the chemical formula for water.
However, if this question is a trick question, a reason why you might say that it isn't water might be because labels may sometimes be untrustworthy, especially in a shared laboratory. You might try to test if it is really water by running a distillation or something.