Why can't contour lines cross?
a. mountains and valleys are different.
b. a location can only have one elevation.
c. it would make the map too difficult to read.
d. terrain can only be going up or heading down.

a location can only have one elevation.

Explanation:Contour lines can never cross on a topographic map. This is because they represent the same elevation of the land surface. A particular point of a land cannot be at two or more than one elevation and this means that only one contour line can pass through that particular point.

All points present along a contour line represent just a single elevation. The most prominent features on a topographic map are the contour lines. The contour lines are the lines that connect points of the same elevation.

And each contour line represents a different elevation so you can't have two (2) different elevations on the same point.

There are 3 kinds of contour lines you can find on a map:

Intermediate

Index

Supplementary.

because the two particles have an equal charge, the charges will cancel out and give the atom an overall charge of 0. so, if at atom has 35 protons in the nucleus, we could expect it to have 35 electrons orbiting that nucleus.