What is the mass of nacl required to make 140 grams of a 12% solution of nacl in water?

a. 12 grams
b. 14 grams
c. 17 grams
d. 18 grams

C. 17 grams.

Explanation:

∵ mass % = [mass of solute/mass of solution] x 100.

mass of solute (NaCl) = ??? g & mass of solution = 140.0 g.

∴ mass of NaCl = (mass %)(mass of solution)/100 = (12.0)(140.0)/100 = 16.80 g ≅ 17.0 g.

mass of NaCl required = 17 grams

Explanation:

Mass% = mass of solute X 100 / total mass of solution

mass%= mass of solute X 100 / mass of solute + mass of solvent

given:

Mass of solution = 140 grams

mass % = 12%

Putting values

12 = mass of NaCl X 100 / 140

mass of NaCl = 12 X 140 /100 = 16.8 grams

mass of NaCl required = 17 grams

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.