a . true hardness and density are physical properties
14.136 J as shown on the photo with two thought processes but overall same calculation
<h2>
Answer: can see</h2>
Explanation:
The portion visible by the human eye of the electromagnetic spectrum is between 380 nm (violet-blue) and 780 nm (red) approximately. Which means this part of the spectrum is located between ultraviolet light and infrared light.
Note the fact only part of the whole electromagnetic spectrum is visible to humans is because the receptors in our eyes are only sensitive to these wavelengths.
Therefore:
<h2>The visible spectrum refers to the portion of the electromagnetic spectrum that <u>we </u><u>
can see</u></h2>
<h2>Answer: free electrons</h2>
<u>Plasma</u> is known as the 4th state of matter and is itself ionized gas. In this sense, ionization consists of the production of ions, which are <u>electrically charged atoms or molecules due to</u><u> the excess or lack of electrons</u><u> with respect to a neutral atom or molecule.
</u>
That is why in this process there are always<u> free electrons</u>. Therefore in heating gas to create plasma can yield free electrons, and the correct option is D.
