Question

A silicon chip used in an integrated circuit of computer has a mass of 5.68 mg. The number of $Si$ atoms present in the chip are:

• A. $1.22\times {10}^{20}$ atoms
• B. $18\times {10}^{20}$ atoms
• C. $2.1\times {10}^{20}$ atoms
• D. None of these

Answer 1

Answer: (A)

$1.22\times {10}^{20}$ atoms

Molar mass of silicon = 28 g = 28000 mg

$\because$ 28000 mg of silicon contain $6.022\times {10}^{23}$ atoms

$\therefore$ 5.68 mg of silicon contain $\frac{6.022\times {10}^{23}}{28000}\times 5.68$

$=0.00122\times {10}^{23}$

$=1.22\times {10}^{20}$ atoms