Question

lubricant is used in machines to keep them working properly . give reason

Answer 1

A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. 

Answer 2

Lubricants are used in various machines for their smooth running. If they are not used for a long time, the can get corroded by rust. Lubricants protect the machines from being rusted.