Test: Separation Of Insoluble Solid - Class 9 MCQ

The solid which collects in the filter paper is called the residue. The clear liquid which passes through the filter paper is called the filtrate. The filter paper acts as a sieve allowing tiny water molecules to pass through the tiny pores in the paper, whilst holding back the much larger particles of solid.

Blood separation is one of the crucial processes in a clinical lab and is usually conducted via a process called centrifugation.

The centrifugation depends upon the size, shape, and density of the particles. It also depends on the viscosity of the medium and the speed of rotation. The theory is that the lighter particles stay at the top when spun rapidly, the denser particles are forced to the bottom.

• In water, some particles are suspended and to remove these particles sedimentation tank is used.
• It is based on the gravity, some particles in suspended waste have a gravity similar to water so they remain suspended.
• But some waste particles are heavier due to their heavier weight, they get settle down in the bottom so sedimentation tank remove it very easily.
• The particles which get settle down on the tank we called that sludge. so we can easily remove this sludge with the help of sedimentation tank.

Centrifugation is a technique used in diagnostic labs for blood and urine tests.The principle of centrifugation is that denser particles are forced to the bottom and the lighter particles float on the surface.

The heavy particles of dissolved alum deposit on the suspended clay particles in water and settles down at the bottom. Thus, adding alums helps in purifying water.

Filtration is the best method to seprate coffee grains from coffee solution because coffee grains will remain as residue and coffee solution can be easily filtered through filter paper.

Stages of water treatment:
(i) Collection
(ii) Screening & Straining
(iii) Chemical Addition
(iv) Coagulation & Flocculation
(v) Sedimentation & Clarification
(vi) Filtration
(vii) Disinfection
(viii) Storage 
(ix) Finally Distribution
Therefore,  option (c) is the correct answer.

• Milk is a suspension of tiny droplets of oil (cream) in a watery liquid.
• The process of centrifugation is used to separate cream from milk. 
• The milk is put in a close container in a big centrifuge machine.
• When the centrifuge machine is switched on, the milk is rotated (or spun) at a very high speed in its container.
• The centrifugal force acts on the milk and due to this, the milk separates into the cream and skimmed milk.
• The cream, being lighter, floats over the skimmed milk and can then be removed.

• Sedimantation and decantation method are used to separate a mixture containing an insoluble solid in a liquid.
• In this method, the mixture is allowed to stand undisturbed for some time.
• The insoluble solid substance settles down and a clear liquid is left standing. This clear liquid is called as supernatant liquid.
• The solid substance that settles down is called sediment. This entire process is known as sedimentation.
• The clear water (supernatant liquid) is then poured out carefully into another beaker, leaving the sediments undisturbed. This process is known as decantation.