Chemistry Discoveries — Set 7

Correct Answer: A. Ernest Rutherford

Ernest Rutherford discovered the proton through experiments that showed the hydrogen nucleus is present in other nuclei. He is widely considered the father of nuclear physics. Protons are positively charged particles located in the atom's center.

Correct Answer: A. Nobel Prize in Physics

Wilhelm Röntgen was the first person in history to receive the Nobel Prize in Physics in 1901. His discovery of X-rays in 1895 allowed scientists to see inside the human body for the first time. It also enabled the later discovery of DNA's structure through X-ray diffraction.

Correct Answer: B. Carl Wilhelm Scheele

Carl Wilhelm Scheele discovered oxygen (which he called 'fire air') in 1772, but his work was published after Priestley's. He was an extremely prolific chemist who discovered several elements and chemical compounds. Unfortunately, he died at the age of 43 due to exposure to toxic chemicals.

Correct Answer: A. Dmitri Mendeleev

Dmitri Mendeleev published his periodic table in 1869, organizing elements by their chemical properties and atomic weight. His genius lay in leaving empty spaces for elements that had not yet been discovered. This organization proved that elements follow a recurring or 'periodic' pattern.

Correct Answer: A. Alexander Fleming

Alexander Fleming discovered penicillin in 1928 after noticing that a fungus had killed bacteria in his lab cultures. This was the first 'miracle drug' that could cure previously fatal bacterial infections. It saved millions of lives during and after World War II.

Correct Answer: B. J.J. Thomson

J.J. Thomson discovered the electron in 1897, showing that atoms are made of even smaller subatomic particles. He visualized the atom as a 'plum pudding' where negative electrons were embedded in a positive sphere. This was the first subatomic particle ever discovered.

Correct Answer: C. Ernest Rutherford

Ernest Rutherford discovered the nucleus in 1911 using his famous alpha-particle scattering experiment. He concluded that an atom's mass and positive charge are concentrated in a tiny central region. This changed the entire understanding of atomic structure from a solid sphere to a mostly empty space.

Correct Answer: A. Henri Becquerel

Henri Becquerel discovered radioactivity by accident in 1896 when he left uranium salts on top of a photographic plate. The plate became fogged even though it was kept in the dark, indicating spontaneous energy emission. He shared the 1903 Nobel Prize with the Curies for this discovery.

Correct Answer: C. Antoine Lavoisier

Antoine Lavoisier proved that the mass of products in a chemical reaction is always equal to the mass of the reactants. He is known as the 'Father of Modern Chemistry' because he moved the field from guesswork to measurement. He also helped name oxygen and hydrogen.

Correct Answer: D. James Chadwick

James Chadwick discovered the neutron in 1932, a neutral particle in the nucleus that has roughly the same mass as a proton. This discovery explained why atomic weights were often double the atomic numbers. It was a vital step toward understanding nuclear fission.