Question

Which of the following given below is colloid?
a . milk
b . coke
c . whisky
d . brass

Answer 1

A colloid is a combination in which one component is suspended in another by microscopically distributed insoluble particles. Some definitions, however, stipulate that the particles must be dispersed in a liquid, while others broaden the concept to include aerosols and gels. The phrase colloidal suspension clearly refers to the entire combination (although a narrower sense of the word suspension is distinguished from colloids by larger particle size).

Complete answer:
Coke is a grey, hard, and porous fuel with a high carbon content and minimal impurities that is produced by distilling coal or oil in the absence of air. It is a vital industrial commodity that is mostly used in the smelting of iron ore, but it is also utilised as a fuel in stoves and forges where air pollution is an issue. The unqualified word "coke" typically refers to a product made from low-ash, low-sulphur bituminous coal by a coking process. Petroleum coke, often known as pet coke, is a similar product made from crude oil in oil refineries. Natural geologic processes can also produce coke. Hence it is not a colloid.
Whisky, often known as whiskey, is a distilled alcoholic beverage that is created from fermented grain mash. Barley, corn, rye, and wheat are among the grains used for various types (some of which are malted). Whisky is usually matured in hardwood barrels, which are either ancient sherry casks or charred white oak casks. Whisky is a highly controlled liquor that comes in a variety of classifications and kinds. Grain fermentation, distillation, and ageing in oak barrels are common unifying elements of the many classes and kinds.
Whiskey and coke are unmistakably homogenous mixtures and not colloids.
Brass is a copper-zinc alloy with variable proportions of copper and zinc to create different mechanical, electrical, and chemical characteristics. It's a substitutional alloy, which means that atoms from the two components can swap places inside the same crystal structure. Brass is comparable to bronze, which is a copper-based alloy with tin instead of zinc.
Hence it is a solid solution and not a colloid.
The dispersed phase of many emulsions, on the other hand, tends to consolidate, form big droplets, and separate. As a result, emulsions are generally stabilised by an emulsifying agent, a material that prevents the scattered liquid from coalescing. A small amount of soap, for example, will stabilise a kerosene-in-water emulsion. The protein casein acts as an emulsifier in milk, which is an emulsion of butterfat in water. Mayonnaise is an oil-in-vinegar emulsion with egg yolk components acting as emulsifiers.

Hence option a is correct.

Note:
Milk is a nutrient-dense liquid food produced by animals' mammary glands. It is the major source of nourishment for young animals, including breastfed human newborns who have not yet developed the ability to digest solid food. Colostrum is a kind of early-lactation milk that includes antibodies that improve the immune system and thereby lower the risk of numerous illnesses. It also contains a variety of other nutrients, including protein and lactose. Milk eating across species is frequent, especially among humans, who drink the milk of other animals.