Millimeters is length, grams is weight. Depending on how thin a string you can make it in, 50 grams can be pretty much any length.
You can't compare these as grams are weight and millimeters are length.
50 kilometers = 50,000,000 millimeters
50km is 50 million millimeters.
10 teaspoons of water is approximately 50 grams
500 millimeters
50 kilometers is 50,000,000 millimeters.
5 cm = 50 millimeters
Centimeters are larger than millimeters; there are 5 centimeters for every 50 millimeters.
5 centimeters is 50 millimeters.
500
50 grams = 1.764 ounces
50 millimeters is equal to 1/2 a centimeter (0.5 centimeters)