Which is a description of an undefined term? • The distance along a line segment is the number of units between two points.
• Perpendicular lines are lines that intersect at a right angle.
• A ray extended infinitely in one direction from an endpoint.
• An angle is the figure formed by the intersection of two rays at common endpoint.

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.