Oil is optically denser than water. When sound/light goes from optically denser medium to optically rarer medium, their velocity increase and they moves away for normal.
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<u>Appropriate</u><u> </u><u>Answer</u><u>:</u></h3>
The sound wave speeds up and bends

As, In optics we learnt that light undergoes refraction when travels from medium of different densities. Similarly, Sound also follows the law of refraction.
- It is due to the change of speed of water in different mediums, This makes it speed up or down depending upon the medium and their densities.
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In general, that's not possible, unless the three numbers relate to
very specific quantities.
For example, if the three numbers are the object's height, temperature,
and cost, then they are of no help at finding the object's velocity.
Answer: f = - 0.50 m, negative (diverging) lens
Explanation: D-value (diopter ) means 1/f, unit is 1/m. Thus -2.0D
Means f = ( 1/ -2.0 ) m = -0.50 m