What helps us to identify the singer by merely listening to the song or to identify what is being cooked in the kitchen by the mere smell?

A student of taxonomy was puzzled when told by his professor to look for a key to identify a plant. He went to his friend to clarify what 'Key' the professor was referring to? What would the friend explain to him?

Questions based on paragraph : Sound is propagated in a material medium in the form of compression and rarefactions. One compression and one rarefaction together form one cycle of the sound wave. The number of cycles produced per second is called as frequency. A tuning fork is a two-pronged device which vibrates to produce sound when struck. The frequency of a tuning fork is decided by the dimensions of the prong and the material used for making the fork. When these sound waves reach ears of listener, his ear-drum vibrates. Accordingly specific signals are conveyed to the brain and the listener gets a sense of hearing sound. : When vibrations are produced, what physical properties of air are changed?

What is hydroponics? How is it useful in identifying the role of nutrients.

Read the statements given below. Identify and write the concept upon which the given statement is based. Madhu is standing in the terrace of his building. What energy does he possess?

Read the statements given below and identify the concepts explained in them. During the same experiment Viraj observes that as the white light passes from rarer to denser medium, it gets dispersed. In the denser medium, as Viraj moves from violet light to red light, what happens to the refractive index of the medium?

Observe the given figure and answer the following questions. a. What does the given figure indicate ? b. Name any fuel produced by this method. c. Identify 'X' in the given figure. d. Give any two examples of plants used for production of fuel by this method. e. Name the process by which glucose is converted into liquid fuel in this method.