Practice MCQ Questions and answers on Chemistry-GK

White phosphorus is highly reactive, and spontaneously ignites at about 30°C in moist air. It is usually stored under water, to prevent exposure to the air.

A colloid is a substance microscopically dispersed evenly throughout another substance. A colloidal system consists of two separate phases: a dispersed phase (or internal phase) and a continuous phase (or dispersion medium) in which the colloid is dispersed. A colloidal system may be solid, liquid, or gas. Milk is an emulsified colloid of liquid butterfat globules dispersed within a water-based solution.

An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids.

An emulsion is a colloidal solution of two liquids, one of which is an oil and the other one is water. For example, milk is an emulsion.

Dialysis is the process which is used for the separation of crystalloids from a colloid by filtration or diffusion through parchment paper or animal membrane. The apparatus employed for this purpose is called dialyser. This process is based on the fact that membranes contain very small pores through which only dissolved molecules and ions of the true solution can pass readily.

An emulsion is a mixture of two or more liquids that are normally immiscible (nonmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, milk, mayonnaise, and some cutting fluids for metal working.

Blood is a natural colloid. Sodium chloride solution, cane sugar solution and urea solution are artificially prepared.

Suspension particles have the size between10^-2 and 10^-4 cm .

Activated coconut charcoal is a highly absorbent material with millions of tiny pores that can capture, bind, and remove unwanted materials. The porous surface has a negative electric charge that attracts positively charged toxins and gas to be carried easily out of the body. It is used medicinally as well as in air and water purifiers.

Gelatine, being a colloid, has the property of preventing crystallization. In ice lollies and ice-cream this is demonstrated by the formation of a very fine crystal structure on freezing. This goes much further in that gelatine stabilized ice-cream does not become grainy or sandy due to the slow crystallisation of lactose with time.