Natural sources of light include our sun and other stars, where the source of energy is nuclear energy (recall that the moon does not produce light but merely reflects sunlight), lightning, where the source is electrical, and fire, where the energy source is chemical.
Answer:
(3) The period of the satellite is independent of its mass, an increase in the mass of the satellite will not affect its period around the Earth.
(4) he gravitational force between the Sun and Neptune is 6.75 x 10²⁰ N
Explanation:
(3) The period of a satellite is given as;

where;
T is the period of the satellite
M is mass of Earth
r is the radius of the orbit
Thus, the period of the satellite is independent of its mass, an increase in the mass of the satellite will not affect its period around the Earth.
(4)
Given;
mass of the ball, m₁ = 1.99 x 10⁴⁰ kg
mass of Neptune, m₂ = 1.03 x 10²⁶ kg
mass of Sun, m₃ = 1.99 x 10³⁰ kg
distance between the Sun and Neptune, r = 4.5 x 10¹² m
The gravitational force between the Sun and Neptune is calculated as;

From what I can see it's D, I did this by simply examining the other answers and seeing that they are beneficial, so, from that information, this one must not be.
Answer:
A. The model was the result of hundreds of years of experiments.
Explanation:
Since it is not possible to visualize an atom in isolation, scientists have spent hundreds of years experimenting and creating atomic models, that is, images that serve to explain the constitution, properties and behavior of atoms.
The earliest who imagined the existence of the atoms were the Greek philosophers Leucippus and Democritus in about 450 BCE. According to them, everything would be formed by tiny indivisible particles. Hence the origin of the name "atom", which comes from the Greek a (no) and tome (parts).
But in the nineteenth century, some scientists began to conduct experimental tests increasingly accurate thanks to technological advances. Not only was it discovered that everything was actually made up of tiny particles, but it was also possible to understand more and more about the atomic structure.
Scientists used the information discovered by other scholars to develop the atomic model. In this way, the discoveries of one scientist were replaced by those of others. The concepts that were correct remained, but those that proved to be non-real were now abandoned. Thus, new atomic models were created. This series of discoveries of the atomic structure until arriving at the accepted models today was known like the evolution of the atomic model.
If I can't open the lid of a jelly jar, I'd keep trying and if I can't open the lid of a jelly jar after the MANY tries I took, I'd ask for help.