Marble is not an element; it is a metamorphic rock composed primarily of calcium carbonate (CaCO₃). It forms when limestone is subjected to high pressure and temperature, causing recrystallization. Being a compound and mixture of minerals, marble does not consist of a single type of atom, unlike elements.

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• Oxygen (O₂): A chemical element essential for respiration and combustion.
• Nitrogen (N₂): A chemical element that makes up about 78% of Earth’s atmosphere.
• Hydrogen (H₂): The lightest chemical element and the main component of stars.

Explanation: Bryology is the branch of botany that deals with the study of bryophytes, which include mosses and liverworts. These are small, non-vascular plants that typically grow in moist and shady environments.

Explanation: The intensity and magnitude of an earthquake are measured using a scientific instrument called a seismograph. It records the vibrations or seismic waves produced by earthquakes. The data obtained from a seismograph are used to calculate the earthquake’s strength on scales such as the Richter Scale or the Moment Magnitude Scale. The seismogram (the recorded graph) shows the amplitude and duration of the waves, helping scientists locate the earthquake’s epicenter and determine its severity.

Explanation: Liquid Natural Gas (LNG) predominantly contains methane (CH₄) in liquid form. It is produced by cooling natural gas to about −162°C, which reduces its volume for easier storage and transportation. LNG is a clean fuel with high energy efficiency and low emissions.

Sir Isaac Newton invented the Reflecting Telescope in 1668. Unlike earlier refracting telescopes that used lenses, Newton’s design used a concave mirror to reflect and focus light. This eliminated chromatic aberration (color distortion) caused by lenses and significantly improved image clarity. Newton’s reflecting telescope became a major advancement in astronomical observation.

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• Thermometer: Invented by Galileo Galilei (early version) and later improved by Daniel Gabriel Fahrenheit.
• Hydraulic Accumulator: Invented by William Armstrong.
• Transistor: Invented much later (in 1947) by John Bardeen, William Shockley, and Walter Brattain.

Insulin was discovered by Frederick Banting and Charles Best in 1921 at the University of Toronto. Banting and his team successfully isolated insulin from the pancreas, which became a breakthrough in the treatment of diabetes mellitus. For this discovery, Frederick Banting and J.J.R. Macleod were awarded the Nobel Prize in Physiology or Medicine in 1923.

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• Jonas E. Salk: Discovered the first successful polio vaccine.
• Alexander Fleming: Discovered penicillin, the first antibiotic.
• Roentgen: Discovered X-rays in 1895.

Explanation: The Cerebrum forms about 80% of the total brain mass. It is divided into two hemispheres and is responsible for higher brain functions such as thought, action, reasoning, and emotion. The Cerebellum lies below it and controls coordination and balance, while the Medulla oblongata manages vital involuntary functions.

Explanation: Web pages are written using HTML (HyperText Markup Language). It is the standard language used to create and structure content on the web by defining elements such as headings, paragraphs, links, images, and tables.

Explanation: Insulin is a hormone secreted by the beta (β) cells of the Islets of Langerhans in the pancreas. Its main function is to regulate the blood glucose level by promoting the uptake of glucose into cells and converting excess glucose into glycogen in the liver and muscles. A deficiency or lack of insulin causes diabetes mellitus, leading to high blood sugar levels. The pancreas also secretes glucagon, which performs the opposite function by increasing blood glucose levels.

Explanation: The Curie point (or Curie temperature) is the temperature above which a ferromagnetic material loses its magnetic properties and becomes paramagnetic. At this point, thermal energy overcomes the magnetic alignment of atoms. For example, the Curie temperature of iron is about 770°C.