Explanation: Chikungunya is a viral disease caused by the Chikungunya virus, which belongs to the Togaviridae family. It is transmitted to humans through the bite of infected Aedes aegypti and Aedes albopictus mosquitoes. The disease causes sudden fever, joint pain, headache, and rash. In contrast, cholera (caused by Vibrio cholerae), typhoid (by Salmonella typhi), and tuberculosis (by Mycobacterium tuberculosis) are all bacterial diseases.

Explanation: A parity bit is added to binary data in a computer system for error detection. It helps identify whether data has been altered during transmission or storage. The parity bit makes the total number of 1s either even (even parity) or odd (odd parity), allowing simple error checking.

The gravitational force of the Earth is maximum at the poles and minimum at the equator. This happens because the Earth is not a perfect sphere; it is slightly flattened at the poles and bulged at the equator due to its rotation. The distance from the center of the Earth to the poles is slightly less than that to the equator, resulting in a stronger gravitational pull at the poles.

Other options (for context)

• At equator: Gravity is slightly weaker because of the Earth's bulge and centrifugal force due to rotation.
• At tropic of cancer: Gravity here is intermediate, not maximum.
• At tropic of Capricorn: Same as the Tropic of Cancer — gravity is moderate, not maximum.

Diseases like Polio and Chicken Pox are caused by viruses. The Polio virus attacks the nervous system and can lead to paralysis, while the Varicella-zoster virus causes Chicken Pox, characterized by itchy blisters and fever. Viruses are acellular infectious agents that can reproduce only inside the living cells of a host organism.

Other options (for context)

• Bacteria: Cause diseases like tuberculosis, cholera, and typhoid, not polio or chicken pox.
• Protozoa: Cause diseases such as malaria and amoebiasis.
• Algae: Generally non-pathogenic; they do not cause human diseases like polio or chicken pox.

Explanation: A carnivore is an animal that primarily eats the flesh of other animals. The tiger (Panthera tigris) is a true carnivore and an apex predator in its ecosystem. It has sharp canines and retractable claws adapted for hunting and tearing flesh. Tigers play a vital role in maintaining the ecological balance by controlling herbivore populations in forests.

Explanation: The King Cobra (Ophiophagus hannah) is the world’s longest venomous snake and the only snake species that builds a nest to lay its eggs. The female collects leaves, twigs, and debris to construct a mound-like nest, usually near dense vegetation or fallen logs. She lays about 20–40 eggs in the nest and guards them aggressively until they hatch, showing remarkable parental care — a rare behavior among reptiles.

Once the eggs are about to hatch, the female leaves the nest to avoid eating her own offspring, as King Cobras are carnivorous and feed mainly on other snakes.

Explanation: Animals that live in or on trees are called arboreal animals. They are adapted to climbing and moving about among branches. Examples include monkeys, squirrels, chameleons, and tree frogs. Their adaptations may include grasping limbs, prehensile tails, claws, or adhesive pads that help them cling to tree surfaces and move efficiently among branches.

Explanation: Brass, an alloy of copper and zinc, gets discoloured when exposed to air containing hydrogen sulphide (H₂S). The H₂S reacts with the metal surface to form a dark layer of metal sulphides (mainly copper sulphide), causing tarnishing and loss of shine.