The device which can be used to detect very small current flowing in an electric circuit is:

In order to obtain a coating of silver metal on a flower vase made of copper, the electrolyte has to be:

The process of purification of an impure metal is like:

If plus sign (+) denotes the positive electrode and minus sign (-) denotes the negative electrode, then which of the following statement is correct for an iron spoon to be copper-plated ?

A student staying in a coastal region tests the drinking water and also the sea water 'With a circuit in which a part of the connecting wire is wound around a matchbox containing compass. He finds that the compass needle deflects more in the case of sea water. Can you explain the reason?