Where should an object be placed in front of a convex lens to obtain an image on the same side as the object?

You are given water,mustard oil,glycerine,and kerosene. In which of these media would a ray of light incident obliquely at the same angle bend the most?

$A$ $5 \, cm$ tall object is placed perpendicular to the principal axis of a convex lens of focal length $20 \, cm$. The distance of the object from the lens is $30 \, cm$. Find the $(i)$ position,$(ii)$ nature,and $(iii)$ size of the image formed.

If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished,what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?

The figure below shows a lens treated as a combination of two prisms and a glass block. $(i)$ Name the lens formed by the combination. $(ii)$ Is the lens converging or diverging? $(iii)$ Draw the refraction of two incident rays to illustrate the property of the lens mentioned by you in part $(ii).$

The refractive index of water with respect to air is $\frac{4}{3}$ and the refractive index of glass with respect to air is $\frac{3}{2}$. What is the refractive index of glass with respect to water?