Answer
a) Exact number
b) Measured quantity subject to uncertainty
c) Measured quantity subject to uncertainty
d) Measured quantity subject to uncertainty
Work Step by Step
a) The number of sheets of a paper in a ream of paper is a result of counting, so it is an exact number.
b) The liter bottle is not precisely filled up to 1.0000 L. So it is a measured quantity subject to uncertainty.
c) The distance between earth and the sun is measured by astronomers. So it is a measured quantity subject to uncertainty.
d) The distance between the centers of two oxygen atoms in the oxygen molecule can be measured by chemists. So it is a measured quantity subject to uncertainty.
