We use a spectrometer to help us determine what stars and planets are made of by passing a light through various chemical elements, different spectral patterns are created. By matching those patterns up to patterns generated in a laboratory environment we can tell what the composition of a distant star or planet is.
Answer:
Sphere B has 4 times more inertia than sphere A.
Explanation:
Inertia on a Solid sphere is given by:

For this problem:
ma = mb = M
Rb = 2*Ra
With these values:


As you can see, Ib = 4 * Ia.
Conduction is your answer here