The answer would be B.
Since the light source comes from the bottom, you just need to find the sequence from the bottom going up.
It will start with the light source, then go through the slide, which will then go through the objective lens and lastly, the eyepiece lens. In summary, the sequence is:
B. Light --- slide ---- objective lens --- eyepiece lens
Answer:

Explanation:
m = Mass of object = 
m' = Mass of water = 
= Density of object
= Density of water
Weight of the water displaced is the force in the case of floating objects
According to the question

In the case of floating objects

The ratio of the density of the object to that of water is 
Galileo saw that Venus went through phases just like the moon .
Answer:
22kj
Explanation:
set h = 0 at the end of slide.
final height is -12m
initial condition will be Ui = 0
Ki = 1/2mv² = 1/2 x 61 x (27)² = 22234.5J
Final condition is Ui = mgh = 61 x 9.8 x -12 = -7173J
Ki = 1/2mv²
Ki= 1/2 x 61 x (16)² = 7808J
conservation energy says that
Ui + Ki = Uf +Kf +ΔEth
so ΔEth = Ui + Ki - Uf - Kf
ΔEth = 22234.5 - 7808 + 7173
ΔEth = 21600J
ΔEth =22Kj