Explanation: Cerebral malaria is a severe neurological complication of malaria infection caused by Plasmodium falciparum. The parasite infects red blood cells, making them sticky and causing them to block small blood vessels in the brain. This leads to high fever, seizures, coma, and can be fatal if untreated. Transmission occurs through the bite of an infected female Anopheles mosquito.

Explanation: Diamond is the hardest natural form of carbon. In diamond, each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral structure, forming a strong three-dimensional lattice. This arrangement makes diamond extremely hard, dense, and transparent. It is used in cutting, drilling, and polishing tools. In contrast, graphite (another allotrope of carbon) is soft and slippery because its carbon atoms are arranged in layers with weak forces between them.

The magnetic effect of current gives rise to a mechanical force. When an electric current passes through a conductor placed in a magnetic field, it experiences a force that can cause motion — this is known as the motor effect. This principle is used in devices like electric motors, galvanometers, and loudspeakers.

• Frictional force: Arises due to contact between surfaces.
• Spring force: Related to elasticity.
• Gravitational force: Due to attraction between masses, unrelated to current.

Explanation: According to the Bureau of Indian Standards (BIS) – IS 10500:2012, the acceptable limit of total hardness in drinking water, expressed as CaCO₃, is 200 mg/l. The permissible limit in the absence of an alternate source is up to 600 mg/l. Excess hardness can cause scaling and affect the taste of water.

Sericulture is the rearing and cultivation of silkworms for the production of silk. The process involves raising silkworms on mulberry leaves, harvesting their cocoons, and then extracting silk fibers from these cocoons. The most commonly used silkworm species is Bombyx mori. Sericulture is an important cottage industry in countries like India, China, and Japan.

Other options (for context)

• Fishes: Their rearing is called Pisciculture.
• Honey bees: Their rearing is called Apiculture.
• Earth worms: Their cultivation for composting is called Vermiculture.

Explanation: The gas used for artificial ripening of green fruits is ethylene (C₂H₄). Ethylene is a natural plant hormone that regulates fruit ripening by stimulating the conversion of starches into sugars, making the fruit softer and sweeter. In artificial ripening, ethylene gas is introduced in controlled amounts to uniformly ripen fruits such as bananas, mangoes, and tomatoes. However, the use of harmful chemicals like calcium carbide for ripening is banned because it produces toxic substances like acetylene.

Explanation: Dialysis is a medical procedure prescribed for patients suffering from kidney failure or severe kidney disease. When the kidneys lose their ability to filter waste products, excess salts, and water from the blood, dialysis performs this function artificially. It helps maintain the body’s chemical balance and remove toxins such as urea and creatinine. There are two main types of dialysis: hemodialysis (using a dialysis machine and artificial kidney) and peritoneal dialysis (using the lining of the abdomen as a filter).

Explanation: An artery is a large blood vessel that carries blood away from the heart to various parts of the body. Arteries have thick, elastic walls to withstand high pressure. In contrast, veins carry blood toward the heart, and capillaries are tiny vessels that connect arteries and veins.

Explanation: The acid present in the human stomach is hydrochloric acid (HCl). It helps in the digestion of food by breaking down proteins and activating the enzyme pepsin. HCl also kills harmful microorganisms present in the food, aiding in maintaining a healthy digestive system.