Which of the following metals is liquid at room temperature?
A. Zinc
B. Mercury
C. Sodium
D. Aluminium
Answer: Option B
Solution (By JKExamLibrary)
Mercury (Hg) is the only metal that is liquid at room temperature. Gallium and cesium melt slightly above room temperature. Sodium is solid but soft. Zinc and aluminium are solids. Mercury is used in thermometers and barometers.
Explanation:
James Chadwick discovered the neutron in 1932 by bombarding beryllium with alpha particles, producing a neutral radiation that he identified as neutrons. Rutherford had predicted the existence of a neutral particle in 1920. Chadwick's discovery explained isotopes' mass differences. Neutron: mass ≈ 1.00866 u, no charge. It is stable inside the nucleus but decays (half-life ~10 min) when free.
Explanation:
Charles' law: V ∝ T (Kelvin). So at constant P and n, V/T = constant. If temperature is in Celsius, proportionality is not direct because zero Celsius is not absolute zero. Absolute zero (0 K = -273.15°C) is the theoretical temperature at which volume becomes zero. A graph of V vs T (K) is a straight line through origin.
Explanation:
Plaster of Paris is CaSO₄·½H₂O. It is made by heating gypsum (CaSO₄·2H₂O) at 373 K. It sets with water to form gypsum again. Used for plastering fractured bones, making statues.
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