Chemistry Discoveries — Set 6

Correct Answer: C. Henri Becquerel

Henri Becquerel accidentally discovered radioactivity in 1896 while investigating phosphorescence in uranium salts. He noticed that the salts emitted rays that could penetrate opaque paper and fog photographic plates. This discovery led to the pioneering research of the Curies.

Correct Answer: B. Hans Christian Ørsted

Ørsted noticed that a compass needle deflected near an electric wire in 1820, proving electricity and magnetism are linked. This was a foundational discovery for both physics and chemistry. It helped scientists later understand how atoms are held together by electrical forces.

Correct Answer: D. Jöns Jacob Berzelius

Berzelius introduced the system of using the first letter or two of an element's Latin name. He also discovered silicon, selenium, and thorium. His system replaced the complex alchemical symbols used by earlier scientists like Dalton.

Correct Answer: A. Carl Wilhelm Scheele

Scheele was a prolific Swedish chemist who isolated dozens of chemical substances including citric, lactic, and malic acids. He also discovered glycerol (glycerin) while working with olive oil and lead oxide. Many of his discoveries were published after other scientists made similar claims.

Correct Answer: B. Germain Hess

Hess's Law states that the total enthalpy change for a reaction is independent of the pathway taken. This is a fundamental law used to calculate heat changes in reactions that are hard to measure directly. It established that energy conservation applies strictly to chemical processes.

Correct Answer: A. Humphry Davy

Humphry Davy used his invention of a powerful electric battery to isolate these highly reactive metals in 1807. He was a pioneer of electrochemistry and mentored the famous Michael Faraday. Davy also discovered calcium, barium, and strontium.

Correct Answer: A. Jöns Jacob Berzelius

Berzelius isolated pure silicon in 1824 by heating potassium with silicon tetrafluoride. Silicon is the second most abundant element in the Earth's crust after oxygen. It is the primary component of most rocks and the base of modern semiconductor technology.

Correct Answer: A. Henri Moissan

Henri Moissan isolated fluorine in 1886 using electrolysis of a solution of potassium fluoride in liquid hydrogen fluoride. Fluorine is the most reactive and electronegative of all elements. He won the Nobel Prize in Chemistry in 1906 for this dangerous feat.

Correct Answer: B. Robert Boyle

Robert Boyle published this law in 1662, stating that pressure and volume are inversely proportional at a constant temperature. He is often called the first modern chemist due to his focus on rigorous experimentation. His book 'The Sceptical Chymist' marks the end of alchemy.

Correct Answer: A. Hennig Brand

Hennig Brand discovered phosphorus in 1669 by heating concentrated human urine. It was the first element discovered that was not known since ancient times. It glowed in the dark, which is why it was named from the Greek for 'light-bearer'.