Portland cement is primarily composed of tricalcium silicate (3CaO·SiO₂), dicalcium silicate (2CaO·SiO₂), tricalcium aluminate (3CaO·Al₂O₃), and tetracalcium aluminoferrite. These compounds are formed by heating limestone and clay at high temperatures and then grinding with gypsum.
Explanation:
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:
Ernest Rutherford discovered the atomic nucleus through his gold foil alpha-scattering experiment in 1911. He later discovered the proton in 1919 by bombarding nitrogen with alpha particles. J.J. Thomson discovered the electron, and Chadwick discovered the neutron.
Explanation:
Hydrogen has about 141.9 kJ/g, the highest of any fuel. Methane ~55.5 kJ/g, coal ~25-35 kJ/g, wood ~17 kJ/g. Hydrogen produces only water on combustion, making it a clean fuel.
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