Answer:
denisity = 52.33 g/c
Explanation:
Density:

We have that m = 785 and that v = 15 c
.

d = 52.33 
Out of that list, the concave mirror is the only item that can concentrate sunlight and heat into a small area. But if you could get ahold of a convex lens, that would be even better.
Answer:
cause Ice is lighter than sunglasses
Energy of wave depends on its amplitude and it is given as

here k = constant
A = amplitude
so energy will increase or decrease depends on the amplitude of the wave
So here if we need to check which wave has lower energy then we need to compare the amplitude.
If the amplitude is less then energy must be less
So please check in the figure that which wave out of A and B has lesser amplitude to find out the wave of lesser energy