Which unit of measurement is most appropriate for describing the mass of a rock sample that will fit in your hand? kilogram milligram gram microgram?

The unit of measurement that is appropriate for a piece of rock that will fit in your hand is GRAM. The gram is a metric unit for measuring mass of objects. As a general rule, gram unit is used for weighing light objects while kilogram is used for weighing heavy objects. 

Answerwide-open;

F=31 because you subtract 39-8