Glass is an amorphous solid. Which of the following properties is consistent with this?
A. Gradual softening on heating
B. Sharp melting point
C. Long-range order
D. High electrical conductivity
Answer: Option A
Solution (By JKExamLibrary)
Amorphous solids like glass do not have a sharp melting point; they soften over a range of temperatures. Crystalline solids have sharp melting points and long-range order. Glass is an insulator.
Explanation:
Modern periodic law: The physical and chemical properties of elements are periodic functions of their atomic numbers. This was established by Moseley. Mendeleev's periodic law was based on atomic masses. Atomic number (Z) determines electronic configuration, which determines chemical behavior. Mass numbers vary with isotopes.
Explanation:
Galvanization is coating iron or steel with a thin layer of zinc to prevent rusting. Zinc acts as a sacrificial anode—it corrodes preferentially (being more reactive) even if the coating is scratched, protecting the underlying iron. Tin coating (tin plating) protects only if the layer is intact. Chromium plating provides a shiny surface and corrosion resistance but works differently. Galvanized iron is used for roofing sheets, buckets, etc.
Explanation:
Soap is made by saponification using NaOH (for hard soap) or KOH (for soft soap). NaCl is used to precipitate soap; Na₂CO₃ is washing soda.
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