Question

refractive index of water w.r.t. air is 1.33 what is the refractive index of air w.r.t. water ?

Answer 1

if refrective index of water w.r.t air = n = 1.333 = 4/3
then refractive index of air w.r.t water will be 1/n
= 3/4 = 0.75
hope it helps
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Answer 2

Refractive index of air =1

So

the refractive index of air w.r.t. water

=1/(4/3)

=3/4

=0.75