Assume a change at the source of sound reduces the wavelength of a sound wave in air by a factor of 3.

(i) What happens to its frequency? It increases by a factor of 9. It increases by a factor of 3. It is unchanged. It decreases by a factor of 3. It changes by an unpredictable factor.
(ii) What happens to its speed?

Explanation:

The speed of a wave is given by :

......(1)

(i) Here, the wavelength of a sound wave in air reduces by a factor of 3. Equation (1) becomes :

Wavelength and frequency are inversely proportional to each other. So, if wavelength of a sound wave in air reduces by a factor of 3, then the frequency will increases by a factor of 3.

(ii) It remains the same.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.