Silver (atomic weight=108 g/mol) has a density of 10.5 g/cm³. The number of silver atoms on a surface of area 10² m² can be expressed in scientific notation as y × 10ˣ. The value of x is:

D=M/V ⇒ 10.5 g/cc means in 1 cc 10.5 g of Ag is present.
Number of moles = mass/molar mass = 10.5 g / 108 g/mol = 0.0972 moles
Number of atoms = moles × Avogadro's number = 0.0972 moles × 6.022 × 10²³ atoms/mol = 5.85 × 10²² atoms
This is the number of atoms in 1 cc (1 cm³).
1 m = 100 cm, so 1 m³ = 10⁶ cm³
10² m² = 10⁴ m² × 0.01m = 10² m³ = 10⁸ cm³
Number of atoms in 10⁸ cm³ = 5.85 × 10²² atoms/cm³ × 10⁸ cm³ = 5.85 × 10³⁰ atoms
Therefore, the number of atoms can be expressed as y × 10ˣ, where y ≈ 5.85 and x = 30.