Question

The diatomaceous earth is used for insulating boilers and steam pipes, because
A. The diatomaceous earth is very cheap.
B. It is a good conductor of heat.
C. It is a bad conductor of heat.
D. It is composed of calcium carbonate.

Answer 1

Hint: Diatoms are a type of algae that can be found in the world's oceans, waterways, and soils. Diatoms make up a major amount of the Earth's biomass, generating 20 to 50 percent of the oxygen produced annually on the globe. Each year, they consume more than 6.7 billion metric tonnes of silicon from the seas in which they live, accounting for roughly half of all organic material in the oceans.

Complete answer:
Dead diatom shells can reach depths of up to a half-mile (800 m) on the ocean floor, and 27 million tonnes of diatom shell dust are delivered by transatlantic winds from the African Sahara each year, much of it from the Bodélé Depression, which was previously home to a system of fresh-water lakes.

Hence the correct answer is option C.
It is a bad heat conductor. Diatoms' cells are surrounded by frustules, which contain silica deposits. Due to the presence of silica in diatom shells, they are very resistant to degradation and are deposited in ocean bottoms, resulting in the development of diatomaceous earth. Diatomaceous earth is used as a filtration aid, a mild abrasive in items such as metal polishes and toothpaste, a mechanical insecticide, a liquid absorbent, a matting agent for coatings, a stabilising component of dynamite, and a thermal insulator since it conducts heat poorly.

Diatoms are single-celled organisms that can exist as solitary cells or as colonies in the form of ribbons, fans, zigzags, or stars. The size of each cell varies from 2 to 200 micrometres. An assemblage of living diatoms doubles every 24 hours by asexual multiple fission in the presence of adequate nutrients and sunlight; individual cells have a maximum life span of around six days. Diatoms are divided into two types: radially symmetric (centric diatoms) and broadly bilaterally symmetric (pennate diatoms). The fact that diatoms are enclosed by a silica (hydrated silicon dioxide) cell wall, known as a frustule, is a distinctive aspect of their anatomy.

Phycology is a discipline of science that studies diatoms. Diatoms are eukaryotes, meaning they have a membrane-bound cell nucleus, which distinguishes them from prokaryotes like archaea and bacteria. Phytoplankton is the most prevalent type of plankton, and diatoms are a type of phytoplankton.

Diatoms can also be seen growing on macrophytes, floating detritus, and benthic substrates. They are an important part of the periphyton community. Another classification approach splits plankton into eight kinds based on size: diatoms are classified as microalgae in this scheme. There are several classification methods for diatom species.

Note:-
Diatoms belong to a wide group of protists, many of which have chlorophyll a and c-rich plastids. Heterokonts, chrysophytes, chromists, and stramenopiles have all been used to describe the group. Golden algae and kelp are autotrophs, while water moulds, opalinids, and actinophryid heliozoa are heterotrophs. The taxonomy of protists in this area is still up in the air. They've been classified as a division, phylum, kingdom, or something in between in terms of rank. As a result, diatoms are classified into a class (typically Diatomophyceae or Bacillariophyceae) or a division (commonly Bacillariophyta).