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Management of Natural Resources — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceManagement of Natural Resources3 Marks
Question
Explain the following:
  1. Sodium chloride is an ionic compound which does not conduct electricity in soild state where as it does conduct electricity in molten state as well as in aqueous solution.
  2. Reactivity of aluminium decrease if it is dipped in nitric acid.
  3. Metals like calcium and magnesium are never found in their free state in nature.
✓

Answer

a. In molten state, due to heat the electrostatic forces of attraction between the oppositely charged ions are overcome. So ions move freely and conduct electricity. In aqueous solutions ions are free and conduct electricity
b. Due to the formation of a coating of aluminium oxide/ $Al _2 O _3$.
c. Reactive metals like calcium and magnesium react easily with different elements and occur in the form of ores.

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