Refractive index of an optical medium changes with

1. the nature of the medium.
2. the change in the angle of incidence of the ray.
3. colour of the incident ray.

Select the correct answer using the code given below :

Protons and neutrons are bound in a nucleus by the

Bases turn red litmus blue and acids turn blue litmus red. A student tested a liquid with a red litmus paper and it stayed red with no change. This shows that the liquid

Ultrasonic waves are those sound waves having frequency

The phenomenon of trade winds takes place due to

Which one among the following waves are called waves of heat energy?