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?

The position-time (x – t) graph for motion of a body is given below :

Which one among the following is depicted by the above graph?

Two copper wires A and B of length l and 2l respectively, have the same area of cross-section. The ratio of the resistivity of wire A to the resistivity of wire B is