The Solid State

  • Question 221
    CBSEENCH12005569

    Which solid is likely to be the best material for converting sunlight into electricity?

    Solution

    Potassium, rubidium.

    Question 222
    CBSEENCH12005570

    In an alloy of gold and cadmium, gold crystallizes in cubic structure occupying the corners only and cadmium fits into the face centre voids. What is quantitative composition of the alloy?

    Solution

    In an alloy of gold and cadmium, gold crystallizes in cubic structure occupying the corners only and cadmium fits into the face centre voids.

    Number of gold atoms     =1/8 x 8 =1Au

    Number of candium atoms =1/2 x 6 =3Cd

    Hence, quantitative composition on = AuCd3

    Question 223
    CBSEENCH12005571

    What is the difference between glass and quartz, though both contain SiO44– units?

    Solution

    Both naturally-occurring and artificial quartz crystal contains at least ninety-nine percent silicone dioxide, while cut glass crystal only possesses at most eighty percent silicone dioxide. 

    Question 224
    CBSEENCH12005572

    What is the effect of Frenkel defect on electrical conductivity of the solid?

    Solution

    Compounds having frenkel defect conduct electricity to a small extent. When electric field is applied, an ion moves from its lattice site to occupy a hole, it creates a new hole. In this way, a hole moves from one end to the other. Thus, it conducts electricity across the crystal. Due to the presence of holes, stability (or the lattice energy) of the crystal decreases.

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