A substance in a solid phase is relatively rigid, has a definite volume and shape.
<span>The atoms or molecules that comprise a solid are packed close together and are not compressible.<span>Because all solids have some thermal energy, its atoms do vibrate. However, this movement is very small and very rapid, and cannot be observed under ordinary conditions.</span></span>
Well, it is important to note that the measurements for absorption and transmittance are inversely related, a low absorption means the substance was not as effective in scattering and or absorbing the specific wavelength of light, I assume, and that most of the wavelength of light has passed through the substance and or has been transmitted, thus it would have a high transmittance.
It’s called neutralization. The alkali has neutralized the acid by taking away the H+ ions and then turning them into water.