The main impurity present in iron ore obtained from mining is:
A. Carbon
B. Alumina
C. Lime
D. Silica
Answer: Option D
Solution (By JKSSB Mock Tests)
The chief impurity in iron ores (hematite, magnetite) is silica (SiO₂), which is acidic gangue. In the blast furnace, limestone (CaCO₃) is added as flux; it decomposes to CaO, which combines with silica to form fusible calcium silicate slag: CaO + SiO₂ → CaSiO₃. This slag floats on molten iron and is removed. Alumina may also be present but silica is the primary impurity.
Explanation:
LPG (propane/butane) is odorless. A small amount of strong-smelling mercaptan (ethanethiol) is added to help detect gas leaks, preventing accidents. Natural gas also has odorant. Mercaptans contain sulfur, and their smell is detectable at very low concentrations. Calorific value, temperature, performance are unaffected. Safety is primary.
Explanation:
Enzymes are proteins (except ribozymes which are RNA). They have specific 3D structures with active sites. They catalyze biological reactions. Denatured by heat or extreme pH.
Explanation:
Calcination is the process of heating a concentrated ore strongly in the absence or limited supply of air. It is typically used for carbonate ores to drive off volatile impurities like CO₂ and H₂O (e.g., CaCO₃ → CaO + CO₂). Roasting is done in the presence of excess air.
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