As the gas cools down, particle movement slows down with it, and so does the temperature of the gas. This is because the more heat or thermal energy a gas has, the faster the particles move. This is why absolute zero, or 0 degrees Kelvin is defined as zero particle movement, because it has zero energy.
Hope this helps
Atoms is basic particles ,electrons,neutrons and the Regions of the atom are called electron shells and contain the electrons. So “a neutral core surrounded by mostly empty space”sounds pretty sure to me :)
The beat frequency is the concept required to develop this process. The phenomenon is generated when you have two waves but their frequencies do not differ greatly. So the beat frequency will be the difference between those two waves. For this case we have the difference and one of the waves, therefore,

Our values are given as,


Using the formula of the frequency I will have,

Replacing we have,



The possible values are two: 1045Hz and 1055Hz
The moon orbits quite fast: it moves about 0.5 degrees per hour in the sky. In 24 hours it moves 13 degrees. The moon's observed motion eastward results from its physical motion of the moon along its orbit around the Earth. so I think its A .