Hydrogen peroxide decomposes slowly on exposure to light. To prevent this, it is stored in:
A. Dark colored bottles
B. Metal containers
C. Open beakers
D. Clear glass bottles
Answer: Option A
Solution (By JKExamLibrary)
Light catalyzes decomposition of H₂O₂. Dark bottles (amber) block light, stabilizing it. Often a stabilizer like urea or phosphoric acid is added. Metal containers may catalyze decomposition.
Explanation:
Temporary hardness is due to Ca(HCO₃)₂ and Mg(HCO₃)₂. Upon boiling, these decompose into insoluble CaCO₃ and Mg(OH)₂, which precipitate out and can be filtered. Thus, boiling effectively removes temporary hardness, and R correctly explains the chemical mechanism involved.
Explanation:
Diamond, with its tetrahedral covalent network, is the hardest known natural material (Mohs 10). Graphite is soft; quartz is SiO₂, hardness 7.
Explanation:
PVC has polar C-Cl bonds; the chlorine atoms create dipole-dipole interactions between polymer chains, restricting chain movement and making the material rigid and strong. Adding plasticizers (e.g., phthalates) reduces intermolecular forces, making it flexible. Cross-links are in thermosets, PVC is thermoplastic. High molecular weight contributes but polarity is key.
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