The tubes 1, 5 and 6 is the answer to the question which test tubes were used to determine the optimal ph lipase activity. Lipase is an enzyme and optimum ph the maximum possible point on which enzyme become active.
Well you see unicellular organisms are very unique in the fact that they live all on their own and move around with a flagellum or little motor, but to the point unicellular organisms carry out essentially every function in life and they must in order to simply survive. So it's most likely D.
The best answer is the first option. A bike rusting is an example of a chemical change since rusting is a chemical reaction. New substances are formed from this reaction. On the other hand, other choices given are just physical changes because only the shape or the physical form of the substances are being changed.
The data gotten from ice cores could scientists tell the about future climate change.
