Why is it necessary to Irrigate the fields after sprinkling urea ? Think it over and answer with reasons.

Why tea leaves are thrown after boiling them ? Think and write.

Why kerosene in sprinkled in drainage water ? Give reasons.

Why is hand picking necessary after winnowing?

Give reasons Why is it necessary to destrach a plant before performing any experiment on photosynthesis?

Explain why friction is necessary to make the disc in Fig. 7.41 roll in the direction indicated. (a) Give the direction of frictional force at B, and the sense of frictional torque, before perfect rolling begins. (b) What is the force of friction after perfect rolling begins ?

A light bulb and an open coil inductor are connected to an ac source through a key as shown in the figure. The switch is closed and after sometime, an iron rod is inserted into interior of the inductor. The glow of the light bulb (a) increases , (b) decreases , (c ) is unchanged, as the iron rod is inserted. Given your answer with reasons.

Farmers sprinkle urea in rice field when leaves turned into………..colour

Why is ploughing of fields necessary before sowing seeds?

Give reasons. Why is it necessary destarch a plant before performing any experiment on photosynthesis?