Calcium (Ca) has a valency of +2, and the phosphate ion (PO₄) has a valency of -3. To balance the charges, we need three calcium ions and two phosphate ions, giving the formula Ca₃(PO₄)₂. This is determined by criss-crossing the valencies of the constituent ions.
Explanation:
Polythene (polyethylene) softens on heating and can be remolded, thus thermoplastic. Bakelite and melamine are thermosetting (cannot be remolded). Vulcanized rubber is also thermoset due to cross-linking. Thermoplastics have linear or branched chains, no cross-links.
Explanation:
In the ammonium ion (NH₄⁺), the nitrogen atom in ammonia (NH₃) shares its lone pair of electrons with a hydrogen ion (H⁺) which has no electrons. This type of bond, where both shared electrons are donated by a single atom, is a coordinate covalent (dative) bond.
Explanation:
Normality (N) is related to molarity (M) by the formula N = M × n, where n is the n-factor (basicity for acids). Sulfuric acid (H2SO4) is a dibasic acid, meaning it can donate two protons (H+) per molecule. Therefore, its n-factor is 2. Normality = 0.1 M × 2 = 0.2 N.
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