Which gas is produced when calcium carbonate reacts with dilute HCl?
A. Oxygen
B. Hydrogen
C. Chlorine
D. Carbon dioxide
Answer: Option D
Solution (By JKExamLibrary)
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑. Carbon dioxide turns limewater milky. This is a test for carbonates and bicarbonates. The reaction is used in laboratory preparation of CO₂.
Explanation:
Galvanization is the process of applying a protective zinc coating to iron or steel to prevent rusting. Zinc acts as sacrificial anode. Tinning is coating with tin (tin cans). Anodizing is an electrochemical process for aluminum to form protective oxide. Electroplating can be with any metal. Galvanized iron is used for roofing sheets, water pipes.
Explanation:
Normal rainwater is slightly acidic with a pH of about 5.6. This is due to the natural dissolution of carbon dioxide from the air into the rain droplets, forming weak carbonic acid (CO₂ + H₂O ⇌ H₂CO₃). Acid rain has a pH lower than 5.6 due to pollutants.
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).
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