The weight of a single plastic cup would best be measured in grams.
The weight of a signle carrot would best be measured in grams.
The weight of a bicycle would best be measured in kilograms.
The weight/mass of a grasshopper would best be measured in grams.
The weight of a car would best be measured in kilograms (kg).
I would say grams because the baseball is not very big
The weight of an empty backpack could probably be measured in grams. However, a filled backpack would best be measured in kilograms.
For a weight of a letter, grams would be the best unit of measurement. As the letter typically is small and doesn't weigh that much. Example of using grams and kilograms would be. Getting slices of deli meat you would get grams, and for roast of meat you would use kilograms.
The mass/weight of a computer printer would best be measured in kilograms.
I would use grams or kilograms.
The best estimate of the mass of a single peach would be 150 grams.
You will use grams to measure a paper cilp, as kilograms are too big. Ideally, you would use neither measurement. The milligram would be the best way of measuring the mass of paperclip.
A compact disc would best be weighed in ounces.
an air conditioner would be best weighed in pounds
A best estimate for the mass of a key is 26 grams.
It natters what you're measuring, for you kilograms would be better, because 1 kilogram is about 2.2 pounds. A 175 pound man would weigh 79378.66 grams and 79.38 kg so obviously a gram is good for something with a small mass.
If you've been specifically asked to, sure. But unless kilograms are really small, or the leaf is really big, grams or even micrograms, if possible, are best.
You could, but it might be best to use Kilograms (1000's of grams)