The total number of protons plus neutrons in an atom of ⁴⁵₂₀Ca is

A.) 20
B.) 25
C.) 45
D.) 65

Stars x and y are both bluish main sequence stars. star x has a higher absolute brightness than star y. how do the two stars compare? explain

Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero? express your answer in terms of some or all of the variables s, q1, q2 and k =14ï€ïµ0. if your answer is difficult to enter, consider simplifying it, as it can be made relatively simple with some work.

What causes the development of most clouds and precipitation in the atmosphere?