Astudent measures the ph of a solution to be 6.8. which should the student add if she wants to decrease the ph of the solution?

PH refers to the concentration of the hydrocarbons were lower than 7 means it is acidic and greater than 7 it is basic. In the problem, since our goal is to help the student arrive at a more acidic solution, we need to add "ACID".

You need to be more specific.  i really don't know what a "motion map" is.you can draw a graph of an object's position, distance, displacement, speed,velocity, or acceleration versus time, or you can draw a graph of the object's x-position versus its y-position and not give any information about time at all.if the graph presents position or displacement against time,  then constant velocity is a straight line . . i.e. a line that has  constant slope.if the graph shows speed against time, then constant velocityis a horizontal piece of line.if the graph shows acceleration against time, then constant  velocity is a piece of line that lies on the x-axis . . it's value is zero.