Using two different instruments i measured the length of my foot to be 27 centimeters and 27.00 centimeters. explain the difference between these two measurements.

As you used two diferent instruments, one is more sensitive than the other.

Explanation:

The sensitivity of an instrument is the minimum amount of magnitude that can be  differentiate a measurement system.

In method A, you got 27 cm, so if in method B, you got 27.00, method B is more sensitive. It's like saying that one system measures more than the other

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.