Question

(1): Cream is collected at the churner when buttermilk is churned.
(2): Lighter cream particles experience less centrifugal force than remaining denser particles.
A) Both 1 and 2 are true and 2 is the correct explanation of 1
B) Both 1 and 2 are true and is not correct explanation of 1
C) 1 is true and 2 is false
D) 1 is false and 2 is true

Answer 1

Hint: There is a difference between the two components of milk that are cream and skimmed milk. They have different densities that are miscible in each other. The churner rotates the milk fast enough to separate the particles.

Complete step by step answer:
When the milk is rotated very fast using a churner, the particles experience centrifugal force. The cream in the milk is lighter than the heavier skimmed milk. This is due to their difference in densities. Hence, when the milk is rotating, it experiences centrifugal force unevenly. The cream particles are lighter and will experience lower centrifugal force.
As a result, the cream particles will be near the churner itself and hence the cream is collected at the churner. While, the heavier skimmed milk is pushed towards the outwards. This is because when liquids of different specific gravities/densities revolve around the same centre at the same distance with the same angular velocity, that of the churner, a greater centrifugal force is exerted on the heavier liquid than on the lighter one making heavier cream particles get collected at churner.
The centrifuge works using the sedimentation principle, where the centrifugal acceleration separates the lighter and the heavier particles. Hence statements (1) and (2) are correct and 2 is the correct explanation of 1.

So, the correct choice is option (A).

Note: The cream has also higher surface tension and cohesive properties and as a reason, it is more likely to stick to the churner. This sort of separation method is also used in chemistry to separate lighter and heavier fluids, separate particles from liquids, etc.