inches
Gram.
Grams would give the most accurate metric measurement of a candy bar. That would allow a person to know the amount of candy that is contained in the bar.
That depends what quantity you want to measure. -- Weight of the bag of apples . . . the scale in the store, newtons or pounds -- Mass of the bag of apples . . . . . balance scale, kilograms -- Length, width, or height of the bag . . . ruler, inches or centimeters -- Volume of the bag of apples . . . tub of water, graduated cylinder, liters or fluid ounces -- Time the apples stay fresh . . . calendar, clock, hours or days
you would use a kilogram
That would depend on how long your tape measure was.
cm
You would use CM or INCHES to measure a knife
That would be a trick question. Their densities would be the same, since density is not a measurement of volume, but a ratio involving volume.
mililiters
I would use my legs, not a measurement! To measure the distance, I would use metres.
kilometre
meters