To calculate the number of atoms in 55mg of carbon, we need to determine the number of moles of carbon present and then multiply it by Avogadro's number (6.022 x 10^23 atoms/mole).

1. Convert the mass of carbon from milligrams (mg) to grams (g):

55 mg = 0.055 g

2. Calculate the number of moles of carbon using the molar mass of carbon (C = 12.01 g/mol):

Moles of carbon = mass / molar mass

Moles of carbon = 0.055 g / 12.01 g/mol

Moles of carbon = 0.00458 mol

3. Multiply the number of moles of carbon by Avogadro's number to obtain the number of atoms:

Number of atoms = moles × Avogadro's number

Number of atoms = 0.00458 mol × 6.022 x 10^23 atoms/mol

Number of atoms = 2.76 x 10^22 atoms

Therefore, there are approximately 2.76 x 10^22 atoms in 55mg of carbon.