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Question: Amount of water present in pearl is? A. 2-4% B. 10% C. 12-15% D. 15-20%...

Amount of water present in pearl is?
A. 2-4%
B. 10%
C. 12-15%
D. 15-20%

Explanation

Solution

Pearl is a hard, glistening, amorphous solid which is used as an ornament and is very expensive. It is produced naturally by organisms belonging to the phylum Mollusca. It is usually seen in the Mantle or between the Mantle and shell of certain bivalve molluscs power like pearl oyster and rarely on some univalve molluscs.

Complete answer:
● Pearl is mostly obtained from Pearl oyster or Pinctada.
● The body is divided into head, visceral hump, and a muscular foot.
● The soft and glandular covering of the visceral hump is called pallium or mantle.
● The Chamber between Mantle and the visceral hump is called the Mantle cavity or the pallial cavity.
● Pearls are shelly substances produced inside the organism when any foreign particles in its body.
● The foreign substances enter the body of molluscs when they open their shells for feeding or respiration.
● A sand particle may also act as a stimulus for the formation of a pearl. This property is exploited in artificial pearl making.
● As a defense mechanism, the mollusk secretes a special type of fluid to coat the foreign substance or irritant. The fluid is deposited over the foreign body layer by layer until it forms a round like lustrous, amorphous pearl.
● The pearl consists of calcium carbonate and conchiolin.
● Conchiolin is a complex protein produced by the molluscs. These proteins assemble to form a microenvironment where the crystals grow.
● The presence of water is very low in pearls ranging from 2 to 4 percent.
● An artificial pearl will not have a high percentage of calcium carbonate and a nacre in it.
So, the correct answer is option A.

Note:- Natural or wild pearls are very rare. Cultured or farmed pearls from pearl oysters are mostly sold nowadays. Imitation pearls are nowadays very common. Imitation pearls are man made objects that are used to resemble real pearls. The reals pearls are very nacreous and iridescent and can be distinguished from the imitation ones by comparing these properties.