Elements emit colours when heated because electrons in atoms can have only certain allowed energies.Heating an atom excites its electrons and they jump to higher energy levels. When the electrons return to lower energy levels, they emit energy in the form of light. Every element has a different number of electrons and a different set of energy levels. Thus, each element emits its own set of colours. See, for example, mercury and neon above. Those colours are as distinctive to each element as fingerprints are to people.
__Dry and Liquid Measurements__
Explanation:
Density is defined as a material per unit volume of the material.
The determination of the density of a liquid with an aerometer is based on the principle of Archimedes' law: "Any object that is immersed in a liquid will experience a lift which is equal to the weight of the liquid being moved".
The aerometer is in the form of a hollow cylinder, so that the aerometer can be immersed in the right position (the scale is immersed in liquid), then the aerometer is filled with Pb grains. The scale on the aerometer shows the density of the liquid, the smaller the density of the liquid, the deeper the aerometer will be. Therefore the aerometer scale shows an increasing number from top to bottom.
<span>D) The outer planets have longer orbital paths than the inner planets. </span>
