Q1: For separating small pieces of metal from engine oil of a car, the best separating technique is the

ANS:C - filtration

Filtration is a physical separation process used to separate solids from liquids or gases by passing the mixture through a porous medium (filter) that retains the solid particles while allowing the fluid to pass through. This technique is widely used in various industries and laboratory settings for purification, clarification, and particle removal. Here's a detailed explanation of the filtration process:

1. Mechanism: Filtration relies on the principle of sieving, where the porous medium acts as a physical barrier to trap solid particles larger than the pore size while allowing the fluid (liquid or gas) to pass through. The solid particles accumulate on the surface or within the pores of the filter medium, forming a filter cake.
2. Types of Filtration:
   • Gravity Filtration: In gravity filtration, the mixture flows under the force of gravity through the filter medium. This method is suitable for separating suspended solids from liquids and is commonly used in laboratory settings.
   • Vacuum Filtration: Vacuum filtration involves applying a vacuum to enhance the flow of the liquid through the filter medium, increasing the filtration rate. It is often used for large-scale industrial filtration processes.
   • Pressure Filtration: Pressure filtration applies pressure to the mixture to force it through the filter medium, increasing the efficiency of particle removal. It is utilized in industries where high filtration rates are required.
3. Filter Media: Filtration can be performed using various types of filter media, including:
   • Filter Paper: Made of cellulose fibers, filter paper is commonly used in laboratory settings for gravity filtration.
   • Membrane Filters: Membrane filters have uniform pore sizes and are suitable for precise particle separation in applications such as microbiology and pharmaceuticals.
   • Filter Cloth: Filter cloth, made of woven or non-woven materials, is used in pressure filtration processes for industrial applications.
4. Applications:
   • Water Treatment: Filtration is essential in water treatment plants to remove suspended solids, sediment, and impurities from drinking water.
   • Oil Filtration: In automotive and industrial applications, filtration is used to remove contaminants, such as metal particles, dirt, and debris, from lubricating oils and hydraulic fluids to maintain equipment performance.
   • Biological Filtration: Biological filtration is employed in wastewater treatment facilities to remove organic matter and microorganisms from sewage and industrial effluents.
5. Advantages:
   • Simple and cost-effective method for particle separation.
   • Versatile and applicable to a wide range of substances and particle sizes.
   • Can be easily scaled up for industrial processes.
   • Minimal energy consumption, especially in gravity filtration.
6. Disadvantages:
   • Some particles may pass through the filter medium if the pore size is too large.
   • Filter media may become clogged over time, reducing filtration efficiency.
   • Pressure and vacuum filtration may require additional equipment and energy consumption.