Filtration on Environmental Studies related Questions and Answers

Question :   Which of the following order is correct regarding the thickness of layer of the materials used in the mixed media filter? 1. Anthracite coal < Sand > Garnet sand 2. Anthracite coal > Sand >> Garnet sand 3. Anthracite coal = Sand = Garnet sand 4. Anthracite coal < Sand < Garnet sand Answer :   2 - Anthracite coal > Sand >> Garnet sand