Which method is used for the concentration of an ore based on the difference in density between the ore and impurities? MCQ with Answer and Explanation

Explanation:
Nitrogen molecule (N₂) has a triple bond between the two nitrogen atoms (N≡N), with bond order 3. This makes it very stable and relatively inert. O₂ has a double bond (O=O). CH₄ has four single C–H bonds. H₂O has two single O–H bonds. The triple bond in N₂ requires high energy to break, which is why N₂ is used as an inert atmosphere. Bond energy N≡N ≈ 946 kJ/mol.

Explanation:
A buffer solution maintains a relatively constant pH when small amounts of strong acid or base are added. However, it is typically composed of a weak acid and its conjugate base (or a weak base and its conjugate acid). A strong acid completely dissociates and cannot form a buffer system. Thus, only statement 1 is correct.

Explanation:
Ostwald process: Catalytic oxidation of NH₃ with air over a platinum-rhodium gauze catalyst at ~800°C to form NO, then NO₂, finally absorbed in water to give HNO₃. Fe is Haber catalyst for NH₃. V₂O₅ is for SO₂ oxidation. Ni for hydrogenation. Pt-Rh alloy gauze provides high surface area and mechanical strength, reducing cost. Nitric acid is used in fertilizers (ammonium nitrate), explosives, and nitration.