The modern periodic table is based on the periodic law proposed by:
A. Niels Bohr
B. Dmitri Mendeleev
C. Henry Moseley
D. John Dalton
Answer: Option C
Solution (By JKSSB Mock Tests)
Henry Moseley discovered that the atomic number (number of protons) is the fundamental property of an element, not atomic mass. He proposed the modern periodic law: properties are periodic functions of atomic numbers. Mendeleev's law was based on atomic mass, which had anomalies.
Explanation:
Carbon-14 (half-life ~5730 years) is used to determine the age of archaeological and geological organic samples up to ~50,000 years. Cobalt-60 for cancer; Am-241 for smoke detectors.
Explanation:
Plaster of Paris is prepared by heating gypsum (CaSO₄·2H₂O) at 373 K, removing part of water of crystallization to form CaSO₄·½H₂O. CaCO₃ is limestone.
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