Explanation: The branch of science that deals with the study of the production, behavior, and effects of materials at very low temperatures is called Cryogenics. The word comes from the Greek words “kryos” meaning cold and “gen” meaning to produce. Cryogenics involves cooling substances to temperatures below −150°C (123 K). It has applications in liquefying gases (like oxygen and nitrogen), cryopreservation of biological samples, superconductivity research, and rocket fuel storage (e.g., liquid hydrogen and oxygen).

Explanation: All enzymes are proteins (except a few RNA-based enzymes called ribozymes). Enzymes act as biological catalysts that speed up chemical reactions in living organisms without being consumed in the process. They work by lowering the activation energy of reactions, ensuring that metabolic processes occur efficiently at normal body temperatures. Each enzyme is specific to a particular substrate, forming an enzyme-substrate complex to carry out its function effectively.

Sound becomes hazardous and causes noise pollution when its intensity exceeds 80 decibels (dB). Prolonged exposure to such high noise levels can lead to hearing loss, stress, sleep disturbances, and other health problems. Common sources include heavy traffic, loudspeakers, machinery, and construction activities. Sounds above 120 dB can cause immediate ear damage or pain.

Other options (for context)

• Above 50 dB: Considered moderate — typical of normal conversation or office noise.
• Above 100 dB: Very loud and potentially painful, but 80 dB is the threshold for long-term hazard.
• Above 130 dB: Extremely loud, causes immediate physical pain and ear damage.

Explanation: Every computer connected to the Internet is identified by a unique numerical label called an IP Address (Internet Protocol Address). It consists of four numeric parts separated by dots (e.g., 192.168.1.1) and is used to locate and communicate with devices over the network.

Explanation: In an incompatible blood transfusion, the antibodies in the recipient’s plasma bind to the antigens on the donor’s RBCs. This causes the red blood cells to agglutinate (clump together) and eventually undergo hemolysis (bursting). The released hemoglobin can block kidney tubules and cause kidney failure, which can be fatal if untreated. This is why blood group compatibility testing (cross-matching) is essential before transfusions.

Example:

If a person with blood group B (having anti-A antibodies) receives blood from a person with group A (which has A antigens), the recipient’s anti-A antibodies will attack the donor’s RBCs, leading to agglutination.