Question

“Kieselguhr” is
(a) Silicified deposits of diatoms
(b)Calcified deposits of diatoms
(c)Pigment deposits
(d)Deposits of calcium oxalate in Euglenoids

Answer 1

Hint: “Kieselguhr” means gravel and yeast. Because of its heat resistance property, it is used as an insulator and also used in metal polishes as abrasives.

Complete answer:
It is a diatomite consisting of silica shells which is later on crumbled into a fine powder which is white in color. It is primarily used as an insulator, filter, or filler in industrial as well as domestic purposes. Some of its uses have been discussed below -
-It is used in explosives as when nitroglycerin absorbed in this diatomite is found to be stable and hence provide ease in transport and handling.
-It is also used in some facial scrubs, toothpaste and as an abrasive material in the metal polishes.
-Due to its abrasive property, it is also used as an insecticide. It absorbs Lipids from the exoskeleton of some insects and thus making them difficult to survive.
-In gardening, it is often used as bonsai (miniature of trees) because it contains various minerals that are important for the proper growth of the plants.
-In some AGA cookers, it is used as a thermal heat barrier because it contains an adequate amount of silica.
So, the correct answer is ‘silicified deposits of diatoms’.

Note:
-Diatoms are unicellular, eukaryotic, microscopic algae of class Bacillariophyceae.
-Diatoms possess a siliceous cell wall known as “frustules”.