On a topographic map, what do the contour lines indicate? Roads
Rivers
Elevation
Mountains

How many atoms are in 1.4 mil of phosphorus trifluoride (pf3)

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

Long term exposure to waves can cause sunburns and skin cancer. a) visible b) infrared c) gamma rays d) ultraviole