State two disadvantages fof incomplete combustion.

State two disadvantags of monoculture.

Incomplete combustion gives :

State disadvantages of friction.

State any two disadvantage of LED.

It is advisable to keep stirring heap of wastes while burning them . Write down two disadvantages of partial combustion

State two disadvantages of cross pollination.

State any two disadvantage of solar cells

State two disadvantages of semiconductors devices.