Two massless springs of spring constants $K_1$ and $K_2$ are connected one after the other forming a single chain, suspended vertically and a certain mass is attached to the free end. If $x_1$ and $x_2$ are their respective extensions and 'F' is their stretching force, the total extension produced is

A wheel is rotating at $600$ rpm about its axis of rotation. When the power is cut off, it comes to rest in half a minute. Its angular retardation expressed in $\text{rad}/\text{s}^2$ is (retardation is uniform)

A flywheel rotating about a fixed axis has a kinetic energy of $500$ joule, if its angular frequency is $5$ Hz, then calculate the moment of inertia of the wheel about the axis of rotation. ($\pi^2=10$)

Given below are two statements:
Statement I: Acceleration due to earth's gravity decreases as you go 'up' or 'down' from earth's surface.
Statement II: Acceleration due to earth's gravity is same at a height '$h$' and depths '$d$' from earth's surface, if $h = d$.
In the light of above statements, choose the most appropriate answer from the options given below.