The scientist who proposed the 'plum pudding' model of the atom was:
A. Niels Bohr
B. Ernest Rutherford
C. J. J. Thomson
D. John Dalton
Answer: Option C
Solution (By JKExamLibrary)
J.J. Thomson discovered the electron and proposed the 'plum pudding' model (positive sphere with embedded electrons). Rutherford proposed the nuclear model after the gold foil experiment. Bohr gave quantized orbits. Dalton gave the solid sphere model.
Explanation:
In an acidic medium, potassium permanganate (KMnO4) is reduced to Mn2+. The oxidation state of Mn changes from +7 to +2, a change of 5. The equivalent weight of an oxidizing agent is its molar mass (M) divided by the number of electrons gained per molecule. Thus, Equivalent weight = M/5.
Explanation:
Plaster of Paris is calcium sulfate hemihydrate, CaSO₄·½H₂O. It is prepared by heating gypsum (CaSO₄·2H₂O) at 373 K. It sets with water to form gypsum.
Explanation:
The ion-exchange process (using cation and anion exchange resins) removes all dissolved cations and anions from water, producing completely demineralized (deionized) water. Distillation removes most impurities but may still contain trace dissolved gases or volatile organics.
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