A plano-convex lens having radius of curvature of first surface 2 cm exhibits focal length of f1 in air. Another plano-convex lens with first surface radius of curvature 3 cm has focal length of f2 when it is immersed in a liquid of refractive index 1.2. If both the lenses are made of same glass of refractive index 1.5, the ratio of f1 and f2 will be :-
1
3 ∶ 5
2
1 ∶ 3
3
1 ∶ 2
4
2 ∶ 3