When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

A child staying in a coastal region tests the drinking water and also the sea water with his tester. He finds that compass needle deflects more in the case of sea water. Can you explain the reason?

A magnetic needle which is free to rotate always shows

Name three liquids which when tested in the manner shown in figure may cause the magnetic needle to deflect.

When a copper wire is dipped in aqueous AgNO_(3) solution, the solution turns blue. The reason for this is

When we preserve idly , dosa dough at our home, we will notice the smell of alcohol. Can you guess the reason for it ?

A deflection magnetometer is adjusted and a magnet of magnetic moment M is placed on it in the usual manner and the observed deflection is theta. The period of oscillation of the needle before setting of the deflection is T. When the magnet is removed, the period of oscillation of the needle is T_(0) before setting to 0^(@). If the eart's induced magnetic field is B_(H) , the relation between T and T_(0) is

The recent studies showed that the yield of sunflower is considerably come down. Can you guess the reason for that ?

In a mango garden a farmer saw one mango tree with full of mango fruits but with a lot of pests. he also saw another mango tree without pests but with few mangoes. But the farmer wants the mango tree with full of mango fruits and pest free. Is it possible to create new mango tree which the farmer wants? Can you explain how it is possible?