Answer: A) 
Explanation:
The equation for the moment of inertia 
of a sphere is:
(1)
Where:
is the moment of inertia of the planet (assumed with the shape of a sphere)
is the mass of the planet
is the radius of the planet
Isolating from (1):
(2)
Solving:
(3)
Finally:
Therefore, the correct option is A.
B. It reflects light rays outward.
A convex mirror looks like this ⊂. So when light rays hit the outward curves, it bends the light rays outwards, and backwards, and it would appear to be coming from its center called the focus.
Answer:
ax = 6.43m/s²
Explanation:
The acceleration is the time derivative of the velocity function ax = dvx(t)/dt
We have been given the velocity function v(t) and also the velocity v = 12.0m/s and we are requested to calculate the acceleration at this time which we don't know.
So the first step is to calculate the time at which the velocity =12.0m/s and with this time calculate the acceleration. Detailed solution can be found in the attachment below.
C.
Explanation: ionic compounds are metals and nonmetals, refer to your periodic table
The primary colors of light are red, blue and green.
There are the pigments like yellow, magenta and cyan that are the mixture of two primary colors.
For example, magenta is a mixture of red and blue color. Thus, it reflects the red and blue color. Also, magneta absorbs the green color.
These type of colors that reflects two primary colors and absorb one color are known as secondary pigments.
Hence, 2nd option is the correct answer.
