What do scientists use to increase the surface area of solute

In which of these cases are the two wave points considered to be in phase with each other?

Can someone me with questions 12 and 13 plz.

The graph indicates the running route for tobias. which best describes his run? from time 0 to 6, he went fast and then slowed down. from time 6 to 10, he was at his slowest. from time 12 to 14, he went very slow. from time 14 to 18, he went toward the starting point.