It is fine to use the equation given by Plitter, since we are told that the mass is about the same as it is now, and I seriously doubt the original question wants the student to go into relativistic effects, electron degeneracy pressure and magnetic effects that govern a real white dwarf star.
There is no need to make it unnecessarily complicated, when the question is set at high school level. The question asks, given a particular radius, and a given mass, what will the density be (which in this case will be the average density). To answer the question, one needs to know the mass of the sun (which is about 2×1030 Kg. One needs to convert the diameter to a radius, and then calculate the spherical volume of the white dwarf. Then one can use the formula given above, namely density=mass/volume
Explanation:
For air, n1 = 1.00003; for water, n2 = 1.3330
Given: θ2 = 30 degrees, then
θ1 = arcsin [(n2/n1) sin θ2]
= arcsin [(1.3330/1.0003) sin (40)]
= 58.93 degrees
Note that since, in this example, light is traveling from a medium of higher density (water; n2 = 1.3330) to a medium of lower density (air; n1 = 1.0003), then n2 > n1, and the angle of refraction (θ1) is larger than the angle of incidence (θ2), thus the light bends away from the normal (in this example, the vertical) as it leaves the water and enters the air.
The answer is D. Unconditioned
The response to an unconditioned stimulus that occurs naturally without learning and involuntarily triggers reaction is known as an unconditioned response. For example, you smell your favorite food while being cook may make you instantly feel hungry.
Answer:
d)2.13 C s⁻¹
Explanation:
Rate of flow of heat through walls
=
K = .33
A = 6 X .4 X .4 =0.96
T₂-T₁ = 30+40 = 70
d = 5 x 10⁻³
Put these data in the relation above
Rate of flow of heat
= 
= 4435.2 Js⁻¹
Specific heat of gas = 2.5 R = 20.785 J
Rise in temp = 
= 2.13 degree celsius.