Hmm, I will come back to this one just to help. :)
Answer;
A plain
Explanation;
A contour line connects points of the same elevation. Contour lines are usually curves. Closed contours represent hills.
Contour lines can not cross since they represent different elevations. A contour interval is the difference in elevation between one contour and an adjacent contour.
Answer:
Distance from start point is 72.5km
Explanation:
The attached Figure shows the plane trajectories from start point (0,0) to (x1,y1) (d1=40km), then going from (x1,y1) to (x2,y2) (d2=56km), then from (x2,y2) to (x3,y3) (d3=100). Taking into account the angles and triangles formed (shown in the Figure), it can be said:

Using the Pitagoras theorem, the distance from (x3,y3) to the start point can be calculated as:

Replacing the given values in the equations, the distance is calculated.
Answer:
Salt crystals are hard and brittle because they are made up of atoms that combine by ionic bonding.
Explanation: