4 A hobbyist collected data about the motion of a toy train on a straight track and then recorded the data in the graph below.
Motion of a Toy Train
6
5
4
Distance from
Starting point
(w)
2
1
0
2
4
6
Time
NOSSO
Which of these accurately describes the motion of the toy train?

Find the protons, electrons and neutrons for strontium with a mass of 83

Which statement best describes the function of enzymes?

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.