Answer:
C. 17 grams.
Explanation:
∵ mass % = [mass of solute/mass of solution] x 100.
mass of solute (NaCl) = ??? g & mass of solution = 140.0 g.
<em>∴ mass of NaCl = (mass %)(mass of solution)/100 </em>= (12.0)(140.0)/100 = <em>16.80 g ≅ 17.0 g.</em>
You can't usually just use a single spectrum line to confirm the identity of an element because there are cases that the emission line id not clearly defined. When the emission line is very weak compared to surrounding noise, in which case the more datapoints you have to build up confidence for the existence of a particular emission spectra, the better.
Energy storage is the capture of energy produced at one time for use at a later time. A device that stores energy is generally called an accumulator or battery.
