Its D for the second energy level, but the first energy level is 2.
Answer:
Light refracts whenever it travels at an angle into a substance with a different refractive index (optical density). This change of direction is caused by a change in speed. ... When light enters a more dense substance (higher refractive index), it 'bends' more towards the normal line.
There are several information's already given in the question. Based on the information's provided, the answer can be easily deduced.
V1 = 25 ml
= 25/1000 liter
= 0.025 liter
V2 = 18 ml
= 18/1000 liter
= 0.018 liter
M2 = 1.0 M
M1 = ?
Then
M1V1 = M2V2
M1 = M2V2/V1
= (1 * 0.018)/0.025
= 0.72 M
From the above deduction, it can be easily concluded that the correct option among all the options that are given in the question is the first option or option "A". I hope that this is the answer that has actually come to your help.