Bleaching powder is calcium oxychloride, CaOCl₂. It is produced by passing chlorine over dry slaked lime: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O. It is a mixed salt of Ca²⁺, Cl⁻, and OCl⁻ ions. It is used for bleaching and disinfection.
Explanation:
Tritium (³H) is a radioactive isotope with a half-life of ~12.3 years, decaying by beta emission to ³He. Protium (¹H) and deuterium (²H) are stable. Tritium is used in self-luminous paints, tracer studies, and nuclear fusion. It occurs naturally in very small amounts from cosmic rays but is mainly produced in nuclear reactors.
Explanation:
Joseph Proust proposed the law of definite proportions (constant composition) – a given compound always contains the same elements in the same proportion by mass. Dalton's theory explained it. Lavoisier gave law of conservation of mass. Rutherford discovered nucleus.
Explanation:
The modern periodic law states that properties of elements are periodic functions of their atomic numbers (number of protons). This was established by Henry Moseley. Mendeleev's original table used atomic mass, but the modern table resolves anomalies by ordering by atomic number.
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