Water drops come in different sizes.
Let's imagine a drop weighs a quarter of a gram.
The molar mass of water is about 18g/mol, which means that 6.02 x 10^23 water molecules (AKA a mole of water molecules) weigh about 18 grams.
A quarter of a gram is 1/72 of 18, so it contains 1/72 times 6.02 x 10^23 molecules. That equals 8361111111111110000000 molecules.
In scientific notation that is... 8.36 x 10^21 molecules.
Standard temperature is 273 K
Standard pressure is 1 atm
We use the ideal gas equation to find out density of nitrogen gas in g/L
Ideal gas equation:

Molar mass of 
Pressure = 1 atm
Temperature = 273 K

= 1.25 g/L
Therefore, density of nitrogen gas at STP is 1.25 g/L
Answer: Plastic. Out of all the raw materials for 3D printing in use today, plastic is the most common. ...
Powders. Today's more state-of-the-art 3D printers use powdered materials to construct products. ...
Resins. ...
Metal. ...
Carbon Fiber. ...
Graphite and Graphene. ...
Nitinol. ...
Paper.
Explanation: