# A silicon chip used in an integrated circuit of a computer has a mass of 5.68 mg. The number of Si atoms present in the chip are:(A) $1.22\text{x1}{{\text{0}}^{20}}$ atoms(B) $18\text{x1}{{\text{0}}^{20}}$ atoms(C) $\text{2}\text{.1x1}{{\text{0}}^{20}}$ atoms(D) None of these

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Hint: Since the mass of the silicon chip is given, we need to find the number of moles of silicon present in the chip. After that we can find the number of atoms present in the chip by using the below formula:
Number of atoms = (n) x (${{N}_{A}}$)
Where,
n is the number of moles,
${{N}_{A}}$ is the Avogadro number (Value is $6.022\text{x1}{{\text{0}}^{23}}$).

Number of moles of Si present(n) = $\dfrac{5.68}{28000}$
Number of atoms = (n) x (${{N}_{A}}$)
Number of atoms = ($\dfrac{5.68}{28000}$) x ($6.022\text{x1}{{\text{0}}^{23}}$)
=$1.22\text{x1}{{\text{0}}^{20}}$ atoms.