Answer:
Structure. Neptune is one of two ice giants in the outer solar system (the other is Uranus). Most (80 percent or more) of the planet's mass is made up of a hot dense fluid of "icy" materials—water, methane and ammonia—above a small, rocky core. Of the giant planets, Neptune is the densest.
Explanation:
Kinetic energy decreases if either the mass or the velocity of the object decreases or if both decrease. and Kinetic energy increases if either the mass or the velocity of the object increases or if both increase.
Explanation:
By Newton's second law, we have

So, in order to give a 0.15kg body an acceleration of 40m/s^2, you need a force of

Answer:
Copernicus discoveres thr heliocentric theory. It was previously believed that everything orbited the Earth, geocentric theory. Copernicus said he believed the Earth and everything else orbited around the Sun.
Density of powder 1 = 0.5 g / 45 cm^3 = 1/90 g/cm^3
Density of powder 2 = 1.3 g / 65 cm^3 = 1/50 g/cm^3
Therefore the densities of the two powders are different, hence chemical reaction has occurred.
(note: none of the other choices make sense. In fact, a different density does not necessarily indicate a chemical change, see paragraph below).
Density of powders are not definitive unless they are each of the same size and texture. For example, granular sugar, rock sugar, and icing sugar all have different densities. I would conclude that this experiment does not lend to a reliable answer.