Answer: 2
Explanation:
Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons.
<span>A.
The model of the atom evolved as scientists have made new discoveries.</span>
The amount of air resistance<span> an </span>object<span> experiences depends on its speed, its cross-sectional area, its shape and the density of the </span>air<span>. </span>Air<span> densities vary with altitude, temperature and humidity. Nonetheless, 1.29 kg/m</span>3<span> is a very reasonable value. The shape of an </span>object affects<span> the drag coefficient (C</span>d<span>)</span>
Almost all telescopes have a circular mirror. The area of a circle is proportional to

where

is the radius of the circle, the constant of proportionality being


Therefore the area of 150 meter telescope would be

times bigger than the area of the smaller (10 meter) telescope.