* Chloroform is an organic chemical compound initially employed as an ideal anaesthetic.

* It was first prepared in 1831.

* The chemical formula is CHCl3. It is a colourless, sweet-smelling dense liquid produced on a large scale.

* Chloroform may be released into the air as a result of its formation in the chlorination of drinking water, wastewater and swimming pools.

* Chloroform is an industrial chemical that can act as a lacrimator.

* It is non-flammable, which makes it safer to handle than ethanol.

• Hydrochloric acid (HCl) is another component oe gastric juice.

• It plays a crucial role in creating the pH required for pepsin activity.

• Hydrochloric acid creates acidic conditions inside the stomach.

• This is necessary for the activation of the enzyme pepsin from pepsinogen.

• When pepsinogen and hydrochloric acid exist together in thstric juice, pepsin takes its active form.

* Limestone, chalk and marble are different forms of Calcium carbonate.

About Calcium carbonate:

* It is a chemical compound with the formula CaCO₃.

* It is a common substance found in rocks as the minerals calcite and aragonite and the main component of eggshells, gastropod shells, shellfish skeletons, and pearls.

* It is the active ingredient in agricultural lime.

* It has medical use as a calcium supplement or as an antacid.

Productivity of an ecosystem:

* Productivity is one of the components of the ecosystem.

* It can be segregated into two parts:

(1) Primary productivity

(2) Secondary productivity

Primary productivity:

* It is the rate of capture of solar energy or biomass production of the producers.

* It is divided into two types: gross primary productivity (GPP) and net primary productivity (NPP).

* GPP: Rate of the capture of solar energy or total production of organic matter

* NPP: It is the remaining biomass or the energy left after utilisation of producers.

Secondary productivity:

* It is the rate of assimilation of food energy by the consumers.

Other components of the ecosystem are:

(i) Decomposition

(ii) Energy flow

(iii) Nutrient cycling

● There are two main types of cell division i.e., mitosis and meiosis.

● Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells.

● Meiosis ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half from 46 to 23 to form sperm and egg cells.

● When the sperm and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will have the usual 46. Meiosis also allows genetic variation through a process of gene shuffling while the cells are dividing.

● Cotton fibers are natural hollow fibers; they are soft, cool, known as breathable fibers and absorbent.

● Jute is a natural fibre, and one of the strongest around.

● Rayon is not a naturally occurring silk but manufactured from natural material, i.e., cellulose.

● It is a natural based fiber as it is not solely synthesized from chemical compounds.

● Since it is neither a natural occurring nor an entirely artificial fiber, we can say that it is a semi synthetic fiber.

The chemical formula of borax is Na₂B₄O₇.10H₂O.

Some uses of Borax are :-

● Insecticide, used in roach-killing treatments and as a moth repellent (ten percent solution on wool)

● Fungicide

● Herbicide

● Desiccant

● Booster for laundry.

● Cleaner for the house.

● Agent for water softening.

● As a preservative, it is a food additive.

● An electric current is expressed by a unit called ampere.

● One ampere is equal to 6.241509074×10¹⁸ electrons worth of charge moving past a point in a second.

● Joule is the unit of work or energy in the International System of Units (SI). It is equal to the work done by a force of one newton acting through one metre.

● The watt is the standard unit of power (energy per unit time), the equivalent of one joule per second. The watt is used to specify the rate at which electrical energy is dissipated, or the rate at which electromagnetic energy is radiated, absorbed, or dissipated.

● Limestone is found in association with rocks composed of calcium carbonates.

● Limestone is a sedimentary rock composed principally of calcium carbonate or the double carbonate of calcium and magnesium.

● It is commonly composed of tiny fossils, shell fragments and other fossilized debris.

● Limestone is usually gray, but it may also be white, yellow or brown. It is a soft rock and is easily scratched. It will effervesce readily in any common acid.

● The chemical formula of magnesium oxide is MgO.

● Magnesium oxide is made up of Mg²⁺ and O^2- ions and are connected to each other by an ionic bond.

● Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion.

● Magnesium oxide also may be used as a laxative for short-term, rapid emptying of the bowel (before surgery, for example). It should not be used repeatedly.

* Platyhelminthes have a single opening in their digestive system that serves both as a mouth and an anus.

* Animals in the phylum Platyhelminthes are called flatworms because they are dorsoventrally flattened from head to tail. They are simply bilateral, unsegmented soft-bodied invertebrates.

* The body of Arthropods is covered by a hard, water-proof exoskeleton made up of Chitin which provides protection and support to the body and the internal organs present inside the body.

* An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry. Examples of echinoderms include sea stars, sea urchins, sea cucumbers, brittle stars, and feather stars.

* Arachnids are a class of joint-legged invertebrate animals with eight legs. Spiders belong to Arachnids class of animals.

* Hence, Option A is the right answer.