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Which one of the following statements is not correct?
Options:
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Verified Answer
The correct answer is:
Schottky defect in ionic solids does not change the density of the crystal
(a) Schottky defect is a type of point defect in a crystal lattice in which ions leaves their lattice sites leaving vacancy. Hence, it decreases the density of crystal.
(b) Packing efficiency is percentage value of total space filled by the particles.
Packing efficiency
$$
=\frac{\text { Volume of atom occupied }}{\text { Total volume of unit cell }} \times 100
$$
(c) In bcc crystal lattice
$$
\begin{aligned}
R+2 R+R & =\sqrt{3} a \\
4 R & =\sqrt{3} a \\
R & =\frac{\sqrt{3}}{4} a
\end{aligned}
$$
(d) Photovoltaic cell is used for conversion of light energy into electrical energy.
Hence, option (a) is incorrect.
(b) Packing efficiency is percentage value of total space filled by the particles.
Packing efficiency
$$
=\frac{\text { Volume of atom occupied }}{\text { Total volume of unit cell }} \times 100
$$
(c) In bcc crystal lattice
$$
\begin{aligned}
R+2 R+R & =\sqrt{3} a \\
4 R & =\sqrt{3} a \\
R & =\frac{\sqrt{3}}{4} a
\end{aligned}
$$
(d) Photovoltaic cell is used for conversion of light energy into electrical energy.
Hence, option (a) is incorrect.
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