An object at rest will stay at rest, and an object in motion will stay in motion, unless acted upon by an unbalanced force is known as which Law
of Motion?

It is Newton's first law of motion also referred  to as the law of inertia.

Explanation:

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.