Depends
Metres.
Probably centimeters.
You'd measure the length of a car in metres.
4-5 1/2 meters
grams or meters weight or length
Probably the best metric unit of measure to use would be the Centimeter (cm) ...There are 2.54 cm per inch.
a gram
10centimmeters
1 meter
A millimetre.
it is a base 10 measurement system.
A centimetre is probably best