Explanation

Scuba tanks contain a mixture of nitrogen (N₂) and oxygen (O₂), commonly called compressed air or nitrox.

Nitrogen prevents oxygen toxicity at high pressures, which can occur in deep-sea diving.

Explanation

The gear system helps control speed and force by changing the torque applied to the wheels.

The wheel and axle mechanism allows smooth movement and efficient transfer of energy.

Explanation

Giraffes use infrasonic waves (low-frequency sounds) to communicate over long distances.

These sounds are below the human hearing range.

It help in coordination and alerting others about predators.

Explanation

Paksat-IR was launched on August 11, 2011, as Pakistan’s first geostationary communication satellite.

It was developed with the help of China.

It provides telecommunication and broadcasting services.

Explanation

The cochlea contains the vestibular system, including the semicircular canals, which help maintain balance.

It detects head movements and sends signals to the brain for coordination and posture control.

Explanation

A black dwarf is the final stage of a low-mass star, after it has cooled and no longer emits significant heat or light.

It forms when a white dwarf loses all its residual thermal energy over billions of years.

Explanation

Explanation

Polymerization is the chemical process where small molecules (monomers) join to form large chains (polymers), which make up plastics.

Petroleum-derived hydrocarbons are used in this process to create various plastic materials like polyethylene and polypropylene.

Explanation

Angiography is a medical imaging technique used to visualize arteries and veins by injecting a contrast dye.

It helps in diagnosing cardiovascular diseases (CVDs) by detecting blockages or abnormalities in the arterial tree.

Explanation

Aluminium has a valency of 3 because it loses three electrons to achieve a stable electron configuration.

Its atomic number is 13.

Its electron configuration is 2, 8, 3.

This means it donates three electrons to form Al³⁺ ions.