Answer: Option A. -> True
:
A
Suspension is a heterogenous mixture in which the solute particles do not dissolve but remain suspended throughout the solvent.
The distribution of the solute particles is not uniform throughout the mixture. For example: muddy water

Answer: Option C. -> solid-solid
:
C
A solution is a homogeneous mixture of two or more substances. Alloy is a example of a solid-solid mixture as it is a mixture of two or more metals or a metal and a non-metal.

Answer: Option A. -> Sol
:
A
Colloids are classified according to the state of the dispersed medium and the dispersed phase. The dispersed phase of milk of magnesia is in the solid state and the dipersing medium is in the liquid state. As a result, milk of magnesia is classified as a sol.

Answer: Option C. -> Centrifugation
:
C
Centrifugation is used to separate cream from milk. Centrifugation works on the principle of density difference. When amixture is spun rapidly, thedenser particles are forced to the bottom and the lighter particles stay on top.
Similarly, when milk is spun rapidly, the less dense fat globules which make cream rise to the top. These can be removed or 'skimmed' off the milk to make low fat milk called skimmed milk.

Answer: Option A. -> Suspension > Colloidal > True solution
:
A
A true solution is a homogeneous mixture. So, the particles will be completely dissolved.
Suspension and colloidal solutions are heterogeneous mixtures. The particles in colloidal solutions are relatively smaller than suspensions. However, the particles of a suspension can be seen with the naked eye, as opposed to a colloid.
Hence, the size of particles in suspension, true solution and colloidal solution varies in the order: Suspension > Colloid> True solution.

Answer: Option C. -> Sublimation
:
C
Ammonium chloride is a substance which directly converts to vapour upon heating, without going through the liquid state. This process is called sublimation. The vapours can be collected and condensed into a separate flask. On the other hand, NaCl does not get vaporised at thattemperature and can beseparated easily.

Answer: Option B. -> False
:
B
A compound is a substance composed of two or more elements, chemically combined together in a fixed proportion. The properties of a compound are different from those of its constituent elements.
For example, let us consider water (${\text{H}}_2\text{O}$). Water is a compound with hydrogen and oxygen as constituent elements. Oxygen is required for combustion, hydrogen is combustible while water extinguishes fire. Oxygen and hydrogen are gases at room temperature while water is a liquid. Clearly, the properties of water are completely different from those of oxygen and hydrogen.

Answer: Option B. -> 23.07 %
:
B
Volume of solute (ethyl alcohol) = 30 mL
Volume of solvent (water) = 100 mL
Total volume of solution = 30 + 100 = 130 mL
Volume by volume % = $\frac{\text{Volume of solute}}{\text{Volume of solution}}\times 100$
$=\frac{30}{130}\times 100=23.07\%$

Answer: Option D. -> Sugar crystals
:
D
A pure substance consists of only a single type of particle - atoms or molecules. Pure substances are classified as elements and compounds.
Sugar is a pure substance as it is made up of only one kind of molecule which is the sugar molecule $\left({\text{C}}_{12}{\text{H}}_{22}{\text{O}}_{11}\right)$.
The other options salt water, muddy water, and soft drink are not pure substances because these are mixtures andcontains more than onetype of particles.

Answer: Option A. -> 15%
:
A
Mass of the solute (sodium chloride) = 15 g
Mass of the solvent (water) = 85 g
Mass of the solution = Mass of the solute + Mass of the solvent
= 15 + 85 = 100 g
Concentration (mass by mass percentage) = $\frac{\text{mass of solute}}{\text{mass of solution}}\times 100$
= $\frac{\text{15}}{\text{100}}\times 100$ = 15%