How many carbon atoms are present in 0.52 moles of c2h6o?

             6.26 × 10²³ Carbon Atoms

Solution:
              First calculate the number of C₂H₆O molecules present in 0.52 moles using following formula,

                                # of Molecules  =  Moles × 6.022 × 10²³

                                # of Molecules  =  0.52 × 6.022 × 10²³

                                # of Molecules  =  3.13 × 10²¹ Molecules

Secondly Calculate the Number of carbon atoms,
As,

                              1 Molecule of C₂H₆O contains  =  2 Carbon Atoms
So,
        3.13 × 10²¹ Molecules of C₂H₆O will contain  =  X Carbon Atoms

Splving for X,
                      X  =  (3.13 × 10²¹ Molecules × 2 Carbon Atoms) ÷ 1 Molecule

                      X  =  6.26 × 10²³ Carbon Atoms

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.