What is the nature of the displacement-time graph of a body moving with constant acceleration?

How can you find the following?
$(i)$ Velocity from a displacement-time graph.
$(ii)$ Acceleration from a velocity-time graph.
$(iii)$ Displacement from a velocity-time graph.
$(iv)$ Velocity from an acceleration-time graph.

An electric train is moving with a velocity of $120 \, km \, h^{-1}$. How much distance will it cover in $30 \, s$ (in $, km$)?

$A$ body thrown in the vertically upward direction rises up to a height $h$ and comes back to the position of its start. Calculate: $(a)$ the total distance travelled by the body and $(b)$ the displacement of the body. Under what condition will the magnitude of the displacement be equal to the distance travelled by an object?

State whether the following statement is true or false:
$A$ motion is said to be uniform if $x \propto t^{2}$.

$A$ racing car has an acceleration of $4\, m s^{-2}$. What distance will it cover in $20\, s$ after the start (in $, m$)?