The use of lead paint in houses was banned in
a. 1980.
b. 1978.
c. in the mid-1900s.
d. 1971.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

that's what i got you can count the number of atoms