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.
Answer:
Physical properties can be observed, described, and measured without changing the material. ... To find the volume of a solid, pour liquid in a graduated cylinder and let a solid object sink in the liquid and measure how much volume is in the solid
The answer is (kg) Kilogram