Answer:
A. have subjects wear the shoes in an experimental trial to see if symptoms improve.
Hi!
To make 500 mL of a 1,500 M solution of NaCl you'll require
43,83 g
To calculate that, you will need to use a conversion factor to go from the volume of the 1,500 M solution to the required grams. For this conversion factor, you'll use the definition for Molar concentration (M=mol/L) and the molar mass of NaCl. The conversion factor is shown below:

Have a nice day!
Answer:
N2 = 2 atoms.
2H2 = 4 atoms.
NH3 = 4 atoms.
Also: this is an uneven chemical equation, make sure there are the same amount of atoms on each side (in total).