The reduction of a metal oxide by carbon at high temperature is known as:
A. Calcination
B. Roasting
C. Leaching
D. Smelting
Answer: Option D
Solution (By JKExamLibrary)
Smelting is the pyrometallurgical process of extracting a metal from its ore by heating it beyond its melting point and reducing the metal oxide with a carbonaceous reducing agent (like coke or coal). Flux is often added to remove impurities as slag. Calcination and roasting are oxidation processes.
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:
Atomic number (Z) = Mass number (A) – Number of neutrons (N) = 39 – 20 = 19. This is potassium (K). Number of protons equals atomic number. In a neutral atom, electrons also equal Z.
Explanation:
Wood has lower calorific value (~17 kJ/g) compared to coal (~25-35 kJ/g), methane (~55.5 kJ/g), and hydrogen (~142 kJ/g). It contains moisture and oxygen, reducing energy density.
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