The number of significant figures in $200.40$ is

Which of the following measurements is the most accurate?

What is the number of significant digits for a number that does not represent a measurement?

The volume of a sphere is $1.76 \ cm^3$. The volume of $25$ such spheres,taking into account significant figures,is:

Length,breadth,and thickness of a strip having a uniform cross-section are measured to be $10.5 \ cm$,$0.05 \ mm$,and $6.0 \ \mu m$,respectively. Which of the following option$(s)$ give$(s)$ the volume of the strip in $cm^3$ with correct significant figures?

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