Which scientist is known for her work on radioactivity and the discovery of radium and polonium?
A. Lise Meitner
B. Dorothy Hodgkin
C. Marie Curie
D. Rosalind Franklin
Answer: Option C
Solution (By JKSSB Mock Tests)
Marie Curie, along with her husband Pierre, conducted pioneering research on radioactivity (a term she coined). In 1898, they discovered two new radioactive elements: polonium (named after her native Poland) and radium. She was the first woman to win a Nobel Prize and the only person to win in two different scientific fields (Physics and Chemistry).
Explanation:
In a double displacement reaction, ions of two compounds exchange places to form two new compounds. Here, Ba²⁺ and Na⁺ exchange their anions (Cl⁻ and SO₄²⁻) to form BaSO₄ (a white precipitate) and NaCl. This is also a precipitation reaction due to the formation of insoluble barium sulfate.
Explanation:
Nitric acid (HNO₃) was called aqua fortis (strong water) due to its ability to dissolve metals like silver (except gold). Oil of vitriol is H₂SO₄; muriatic acid is HCl.
Explanation:
Cobalt-60 emits high-energy gamma rays used in radiotherapy (teletherapy) to treat cancers by damaging DNA of malignant cells. Carbon-14 is used for radiocarbon dating. Americium-241 is used in smoke detectors. Phosphorus-32 is used as tracer. Radiotherapy must be carefully targeted to minimize damage to healthy tissue.
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