See the attached picture for answers
The International Astronomical Union (IAU) downgraded the status of Pluto to that of a dwarf planet because it did not meet the three criteria the IAU uses to define a full-sized planet. Essentially Pluto meets all the criteria except one—it “has not cleared its neighboring region of other objects.
Answer:
(a) 40.6 degree
Explanation:
When refraction takes place from slab to water, the critical angle is 60 degree.
Use Snell's law
refractive index of water with respect to slab



μs = 1.536
Now for slab air interface, the critical angle is C.


1 / 1.536 = Sin C
C = 40.6 degree
Answer:
Diffraction: Wave Theory
Interference: Wave Theory
Reflection: both particles and wave theories
Refraction: both particles and wave theories
Answer:
they are the source of energy for primary consumers... they also produce oxygen and sugar