It depends upon the chemical, substance, or element the material is made of, but it is a given by you that it will be a weight of 1 g. If you could specify the material a better description could be given.
A gram is a measure of mass - it does not "look" like anything.
As used here, grain is a measure of weight- ABOUT 1 gram. Smokeless gun powder is usually grey to dark grey, and may consist of tiny flakes, disks or rods.
Look at them under a microscope! If they are cocci, they will look like balls. If they are rods, they will look like...rods!
Gram is a solid measurement. Air is not solid.
powder
One one-thousandth of a gram looks like mg, or milligram.
It has a big Baking Powder label on it
It doesn't look like anything...you can't see it.
A quarter gram of a 1 gram
0.5 g
Orzo is the pasta that is shaped like rice.
Atoms do not look like the material that they make.