Which of the following represents a disproportionation reaction?
A. 2H2O2 -> 2H2O + O2
B. Zn + CuSO4 -> ZnSO4 + Cu
C. N2 + 3H2 -> 2NH3
D. CaCO3 -> CaO + CO2
Answer: Option A
Solution (By JKSSB Mock Tests)
A disproportionation reaction is a specific type of redox reaction where the same element in a single substance is simultaneously oxidized and reduced. In the decomposition of hydrogen peroxide (H2O2), oxygen has an oxidation state of -1. It is reduced to -2 in H2O and oxidized to 0 in O2.
Explanation:
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:
Teflon (PTFE) has a very low coefficient of friction and surface energy because the fluorine atoms form a protective shield around the carbon backbone, making it difficult for other substances to adhere. This is not due to polarity (C-F bonds are polar but the molecule overall is non-polar due to symmetry). It is extremely inert, resisting most chemicals.
Explanation:
Caustic soda is NaOH (sodium hydroxide). It is a strong base used in soap, paper, and textile industries. Washing soda is Na₂CO₃, baking soda NaHCO₃. Caustic potash is KOH.
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