The Solid State

  • Question 117
    CBSEENCH12005465

    Explain Ionic solids are hard and brittle. 

    Solution
     In ionic solids, constituent particles are held together with strong electrostatic force of attraction along with their fixed position. The fixed position of ions and strong electrostatic force of attraction make ionic solids hard and brittle.
    Question 118
    CBSEENCH12005466

    Give reasons for ZnO becomes yellow on heating.

    Solution

    Metal excess defect due to the presence of extra cations at interstitial sites: Zinc oxide is white in colour at room temperature. On heating it loses oxygen and turns yellow





    Question 119
    CBSEENCH12005467

    Give reasons for Solids with F-centres are paramagnetic?

    Solution
    f centres are the anionic vacancies occupied by unpaired electron. since the presence of unpaired electrons shows paramagnetic.
    Question 120
    CBSEENCH12005468

    Give reasons for Cation vacancies in some crystals make them good catalysts.

    Solution
    The catalytic activity dependsvery much on the surface area per unit mass of the sample.
    Transition metal corresponds show metal deficiency due to absence of metal ion from its lattice. The charge is balanced by an adjacent ion having higher positive charge which ultimately increases chemisorption.

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