Explanation: A good liquid lubricant must possess the properties like adequate viscosity, high boiling point, low freezing point, good oiliness. It also contains stability towards the oxidation and heat.

Explanation: Grease is the semi-solid lubricant which has high viscosity but the liquid lubricant must have an adequate amount of viscosity. It should not be more or less. Olive oil, palm oil, castor oil are liquid lubricants.

Explanation: The castor oil is mainly used for machinery at high speed and low pressure. It is used at plastic industry and medical purposes. For guns and sewing machine the neats foot oil is used. For light machinery, whale oil is used.

Explanation: The petroleum oils are also called as the hydrocarbon oils. They contain C12 to C15. These oils are obtained from crude petroleum. They are cheap and have very wide applications.

Explanation: Petrol captured 98% of the market. Naphthenes and paraffin compounds are mainly found in mineral oils and they are more efficient in preventing the metals from corrosion.

Explanation: The lubricating oils must be refined to remove the compounds like wax, aromatic compounds and asphaltic compound. If these compounds are not removed then they will be crystallize and stops the flow of lubricating oil.

Explanation: The easily oxidisable impurities cause the sludge formation. During the operating conditions, the asphaltic. Napthatic compounds will allows to form the sludge. As they decompose at high temperatures to cause the formation of carbon also.

Explanation: Additives are added to refined petroleum oils. They are refined by processes like dewaxing etc. They are added to improve the performance of the lubricants. They are called as blended oils as additives are added.

Explanation: A dispersion system consisting of two immiscible liquids is called emulsions. A substance is added to the emulsions called emulsifying agents for stabilization. The emulsifying agents show polar or non polar natures accordingly.

Explanation: Oil in water emulsion is obtained by adding the oil to a sufficient amount water that is about 3 to 20%. The emulsifying agents must be water soluble like sodium soaps or sodium or potassium salts or sulphides.

Explanation: The emulsifiers in water in oil type are alkaline earth metals. Sulphides, sodium and potassium salts are used in oil in water type emulsion. To prepare water in oil type emulsions, 1-10% of water and emulsifiers are added to the oil.