Chemistry Discoveries — Set 6
Inventions · रसायन की खोजें · Questions 51–60 of 70
Which scientist is famously known for the discovery of 'Radioactivity'?
Correct Answer: C. Henri Becquerel
• **Henri Becquerel** = He accidentally discovered radioactivity in 1896 while investigating phosphorescence in uranium salts. • **1896** — the year of discovery; this discovery led to the pioneering research of **Marie Curie**. • 💡 Wrong-option analysis: Max Planck: developed quantum theory; Marie Curie: pioneered research on radioactivity, discovered polonium and radium; Ernest Rutherford: proposed the nuclear model of the atom.
Who discovered 'Electromagnetism', which influenced the study of chemical bonding?
Correct Answer: B. Hans Christian Ørsted
• **Hans Christian Ørsted** = He noticed that a compass needle deflected near an electric wire in 1820, proving electricity and magnetism are linked. • **1820** — the year of discovery; it helped scientists later understand how atoms are held together by **electrical forces**. • 💡 Wrong-option analysis: James Clerk Maxwell: formulated the theory of electromagnetic radiation; Michael Faraday: discovered electromagnetic induction; Andre-Marie Ampere: formulated Ampere's law.
Which chemist is responsible for the modern system of chemical symbols (like H, O, Na)?
Correct Answer: D. Jöns Jacob Berzelius
• **Jöns Jacob Berzelius** = He introduced the system of using the first letter or two of an element's Latin name for chemical symbols. • **Silicon, selenium, and thorium** — these elements were also discovered by him; his system replaced complex alchemical symbols. • 💡 Wrong-option analysis: Antoine Lavoisier: named oxygen and hydrogen, established the law of conservation of mass; Robert Boyle: defined elements and formulated Boyle's Law; John Dalton: proposed the atomic theory with unique symbols for elements.
Who discovered 'Glycerol' and 'Oxalic Acid'?
Correct Answer: A. Carl Wilhelm Scheele
• **Carl Wilhelm Scheele** = He was a prolific chemist who isolated dozens of chemical substances, including glycerol and oxalic acid. • **Glycerol** — discovered by him while working with olive oil and lead oxide; many of his discoveries were published after others made similar claims. • 💡 Wrong-option analysis: Joseph Priestley: discovered oxygen and nitrous oxide; Antoine Lavoisier: father of modern chemistry; Friedrich Wöhler: synthesized urea.
Which scientist discovered the 'Law of Constant Heat Summation' in thermochemistry?
Correct Answer: B. Germain Hess
• **Germain Hess** = His law states that the total enthalpy change for a reaction is independent of the pathway taken. • **Heat changes** — this fundamental law is used to calculate heat changes in reactions that are hard to measure directly; it established energy conservation in chemical processes. • 💡 Wrong-option analysis: James Joule: established the relationship between mechanical work and heat; Josiah Willard Gibbs: pioneered chemical thermodynamics; Lord Kelvin: developed the Kelvin scale of temperature.
The discovery of 'Sodium' and 'Potassium' by electrolysis was made by?
Correct Answer: A. Humphry Davy
• **Humphry Davy** = He used his invention of a powerful electric battery to isolate highly reactive metals like sodium and potassium. • **1807** — the year he isolated these metals; he also discovered **calcium, barium, and strontium**. • 💡 Wrong-option analysis: Joseph Priestley: discovered oxygen; Alessandro Volta: invented the electric battery; Michael Faraday: discovered electromagnetic induction and electrolysis laws.
Who is credited with discovering 'Silicon'?
Correct Answer: A. Jöns Jacob Berzelius
• **Jöns Jacob Berzelius** = He isolated pure silicon in 1824 by heating potassium with silicon tetrafluoride. • **1824** — the year of isolation; silicon is the second most abundant element in the Earth's crust and the base of modern **semiconductor technology**. • 💡 Wrong-option analysis: John Dalton: proposed the atomic theory; Humphry Davy: discovered sodium and potassium; Antoine Lavoisier: named oxygen and hydrogen.
Which chemist discovered 'Fluorine' after many others failed and even died trying?
Correct Answer: A. Henri Moissan
• **Henri Moissan** = He isolated fluorine in 1886 using electrolysis of a solution of potassium fluoride in liquid hydrogen fluoride. • **1886** — the year of isolation; fluorine is the most reactive and electronegative of all elements; he won the **Nobel Prize in Chemistry in 1906** for this feat. • 💡 Wrong-option analysis: George Gore: attempted to isolate fluorine and suffered severe injuries; Humphry Davy: also attempted to isolate fluorine and suffered injuries; Carl Scheele: studied fluorspar but did not isolate fluorine.
Who discovered 'Boyle's Law', relating the pressure and volume of a gas?
Correct Answer: B. Robert Boyle
• **Robert Boyle** = He published this law in 1662, stating that pressure and volume are inversely proportional at a constant temperature. • **1662** — the year of publication; his book **'The Sceptical Chymist'** marks the end of alchemy. • 💡 Wrong-option analysis: John Dalton: proposed the atomic theory; Amedeo Avogadro: formulated Avogadro's Law; Charles Boyle: no significant chemist with this name related to this law.
The discovery of 'Phosphorus' was made by which alchemist while searching for the philosopher's stone?
Correct Answer: A. Hennig Brand
• **Hennig Brand** = He discovered phosphorus in 1669 by heating concentrated human urine. • **1669** — the year of discovery; it was the first element discovered that was not known since ancient times; it was named from the Greek for **'light-bearer'**. • 💡 Wrong-option analysis: Isaac Newton: famous for laws of motion and gravitation, not phosphorus discovery; Robert Boyle: attempted to isolate phosphorus but Brand succeeded first; John Dalton: proposed the atomic theory.