Question

A teacher instructed four students A, S, C and D to prepare a suspension of chalk in water. The students prepared suspension in the following manner:
student ′A′ places a piece of chalk in water.
student ′S′ places powdered chalk in water.
student ′C′ places powdered chalk in water and then shakes the mixture vigorously.
student ′D′ places powdered chalk in dil. HCl.
Which of the following students has the correct way of preparation of suspension?
(A)- Student A
(B)- Student B
(C)- Student C
(D)- Student D

Answer 1

Hint: A suspension is said to be a heterogeneous mixture having solute resembling particles settle out of a solvent resembling phase after their introduction into the mixture. We are using the terms 'solute resembling ' and 'solvent resembling ' because we are dealing with heterogeneous mixture and the terms solute and solvent refers to homogeneous solutions.

Complete step by step answer:
A suspension is said to be a heterogeneous mixture of particles with a diameter that is greater than 1000 nm so that the particles are visible with naked eyes. In this type of mixture, all the components are mixed completely such that all the particles can be seen under a microscope. A suspension contains solid particles that are large enough for sedimentation. Let’s take an example to understand suspension. If we take a glass of water and mix mud in it then it will form a heterogeneous mixture and we could easily identify the components present in these mixtures. After a while, we could observe the particles of mud settle down due to gravity. Besides, the particles in suspension are larger than the particles present in a solution. The particles of suspension don’t pass through filter paper. Therefore, a suspension can be separated by filtration. The suspension can also be called unstable as the particles of a suspension settle down after a while. A suspension is often found to scatter a beam of light that passes through it because of large particle size. On dissolving a chalk powder in water, we find a suspension. The mixture is also stirred for a while to ensure the uniform dispersion of chalk powder. We see that the chalk powder does not dissolve in water. It is found to form suspension in water and eventually settles down under the influence of gravity.

Therefore, the correct option is (c).

Note: One should be clear in the difference between the suspension, colloid, and solution. A Colloid is having properties intermediate between that of the solution and suspension. It has particles between 2 and 1000 nanometers in size. A solution is a homogeneous mixture of substances.