Which of the following are characteristics for colloid mills (P) Due to centrifugal forces, the mill undergoes periodical vibratory movement (Q) Particles smaller than 1 \mu {\m} can be obtained with them (R) The main types of colloid mills are hammer, turbine and dial mills (S) The principle of their operation is based on the abrasion of particles at high speed

Correct Answer is : Only Q and S are correct

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