Is a map scale a ratio that converts one distance into another?

Which statement is a proper biconditional statement for the conditional statement: if a line intersects a line segment at its midpoint, then it is a segment bisector. if a line is a segment bisector, then it intersects the line segment at its midpoint. if a line does not intersect a line segment at its midpoint, then it is not a segment bisector. a line intersects a line segment at its midpoint if, and only if, it is a segment bisector. if a line is not a segment bisector, then it does not intersect the line segment at its midpoint.

Which occurs when air is compressed? air molecules move slower. air temperature rises and air molecules move faster. air temperature decreases. air temperature decreases and air molecules move faster.

Explain: plate tectonics and people.