The number of significant figures in the simplification of $\frac{0.501}{0.05}(0.312-0.03)$ is

The radius of a circle is $2.12 \ m$. Its area according to the rule of significant figures is ......... $m^2$.

$Assertion$ : The number of significant figures depends on the least count of the measuring instrument.
$Reason$ : Significant figures define the accuracy of the measuring instrument.

If the side length of a cube is $7.203 \ m$,then its volume is ............ $m^3$.

$A$ body of mass $m = 3.513 \; kg$ is moving along the $x$-axis with a speed of $5.00 \; ms^{-1}$. The magnitude of its momentum is recorded as (Consider significant figures):

Time periods of oscillation of the same simple pendulum measured using four different measuring clocks were recorded as $4.62 \,s, 4.632 \,s, 4.6 \,s$ and $4.64 \,s$. The arithmetic mean of these readings in correct significant figures is: (in $\,s$)