Answer:
1.In dry cells, manganese dioxide acts as a ‘depolariser'.
In the depolarization process, the depolariser is used to remove hydrogen and doesn't allow the voltage to get reduced due to polarisation of the cell . Manganese oxide was used as a depolariser in Leclanché cell .
In zinc-carbon dry cell, the manganese dioxide takes in electrons as it is converted to Manganese III oxide (Mn2O3)
2.The fuse breaks the circuit if a fault in an appliance causes too much current flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.
