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JEE Advanced · Chemistry · 15. Solid State

Silver (atomic weight \(=108 \mathrm{~g} \mathrm{~mol}^{-1}\) ) has a density of \(10.5 \mathrm{~g} \mathrm{~cm}^{-3}\). The number of silver atoms on a surface of area \(10^{-12} \mathrm{~m}^2\) can be expressed in scientific notation as \(y \times 10^x\). The value of \(x\) is

  1. A 3
  2. B 5
  3. C 7
  4. D 9
Verified Solution

Answer & Solution

Correct Answer

(C) 7

Step-by-step Solution

Detailed explanation

Volume of one mole of silver atoms \(=\frac{108}{10.5} \mathrm{~cm}^3 /\) mole Volume of one silver atom \(=\frac{108}{10.5} \times \frac{1}{6.022 \times 10^{23}} \mathrm{~cm}^3\)
So,
\(\frac{4}{3} \pi R^3 =\frac{108}{10.5} \times \frac{1}{6.022 \times 10^{23}}=1.708 \times 10^{-23} \)
\( R^3 =0.407 \times 10^{-23} \mathrm{~cm}^3 \)
\( =0.407 \times 10^{-29} \mathrm{~m}^3\)
Area of each silver atom
\(
\pi R^2=\pi \times\left(0.407 \times 10^{-29} \mathrm{~m}^3\right)^{2 / 3}
\)
So number of silver atoms in given area
\(
=\frac{10^{-12}}{\left(0.407 \times 10^{-29} \mathrm{~m}^3\right)^{2 / 3}}=\frac{10^8}{(\pi \times 2)}=1.6 \times 10^7=\) \(y \times 10^x \quad \text { so, } \quad x=7
\)
Solid state
Mathematical understanding
III
From JEE Advanced
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