The acid used in the pickling of metals to remove oxide layers is:
A. Nitric acid
B. Carbonic acid
C. Acetic acid
D. Hydrochloric acid
Answer: Option D
Solution (By JKSSB Mock Tests)
Hydrochloric acid (HCl) is commonly used for pickling (cleaning) steel to remove rust and scale (iron oxides) before further processing like galvanizing or plating. Reaction: Fe₂O₃ + 6HCl → 2FeCl₃ + 3H₂O. Sulfuric acid is also used. Nitric acid is an oxidizer and would passivate some metals. Acetic acid is too weak.
Explanation:
Bauxite (Al₂O₃·2H₂O) is the principal ore of aluminium. Haematite is Fe₂O₃, galena is PbS, cinnabar is HgS. Bauxite is refined by Bayer's process to produce alumina, then electrolytically reduced (Hall-Héroult process).
Explanation:
Synthetic detergents (like alkyl sulfates or sulfonates) form soluble calcium and magnesium salts, so they lather well even in hard water. Soaps form scum. Detergents are usually derived from petrochemicals, can be non-biodegradable if branched, and may cause pollution.
Explanation:
The Contact process involves the oxidation of SO₂ to SO₃. The catalyst used for this step is Vanadium pentoxide (V₂O₅) or sometimes platinized asbestos. Iron is used in the Haber process, and Nickel is commonly used in the hydrogenation of vegetable oils.
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