Electrovalency is the number of electrons lost or gained by an atom. The electrovalency of magnesium in MgCl₂ is:
A. 2
B. 1
C. 6
D. 4
Answer: Option A
Solution (By JKExamLibrary)
Magnesium loses two electrons to achieve noble gas configuration (Mg → Mg²⁺), so its electrovalency is +2. In MgCl₂, Mg²⁺ and two Cl⁻. Electrovalency is the charge on the ion. Covalency is number of covalent bonds. For Group 2 metals, electrovalency is always +2 (loss of 2 electrons).
Explanation:
Dalton considered atoms the ultimate, indivisible particles. The discovery of electrons (J.J. Thomson), protons (Rutherford), and neutrons (Chadwick) proved atoms are divisible and have internal structure. Isotopes showed atoms of same element can differ. However, Dalton's theory still formed the foundation of modern chemistry.
Explanation:
Smelting involves heating the concentrated ore (often after roasting/calcination) with a reducing agent (like coke, CO) to reduce the metal oxide to the metal. For example, iron ore is smelted in a blast furnace. Roasting heats sulfide ores in air; calcination heats carbonate ores in absence of air; leaching dissolves out the metal.
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