The bottom of a container filled with liquid appears slightly raised because of

Which of the following statements is correct?

An electromagnetic wave,whose wave normal makes an angle of $45^{\circ}$ with the vertical,travelling in air strikes a horizontal liquid surface. While travelling through the liquid it gets deviated through $15^{\circ}$. What is the speed of the electromagnetic wave in the liquid,if the speed of electromagnetic wave in air is $3 \times 10^8 \ m/s$? $(\sin 30^{\circ} = 0.5, \sin 45^{\circ} = \frac{1}{\sqrt{2}})$

What is absolute refractive index? On what factors does it depend?

On heating a liquid,the refractive index generally

State Snell's law of refraction.