The refractive indices of the Hydrogen gas, olive oil,benzene,flint glass is as follows:-
Flint glass 1.57----1.75
Benzene    1.001762
Oil (olive0   1.46
Hydrogen     1.000132
The speed of light is as follows:-
To calculate the speed of light in different mediums will be calculated by using the formula  μ(refractive index of the medium)=c/v         where c is the speed of light in vacuum i.e. 3×10⁸ m/sec

1) in Benzene 
μ  =300000000/v
⇒ v=300000000/1.001762
⇒ v=299472329.75497174 m/sec                             Ans.

2) in Hydrogen gas
⇒v=299960405.2265101 m/sec                                Ans.

3) in Flint glass taking refractive index to be 1.6
⇒v=187500000 m/sec                                              Ans.

4) in olive oil
⇒v=205479452.05479452 m/sec                               Ans.      
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