**Explanation:**

As molar mass of [tex]C_{2}H_{4}[/tex] is 28.05 g/mol and it is given that its mass is 2.8 g.

Therefore, calculate its number of moles as follows.

No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]

= [tex]\frac{2.8 g}{28.05 g/mol}[/tex]

= 0.099 mol

= 0. 1 mol (approx)

And, according to the mole concept there are [tex]6.022 \times 10^{23} atoms[/tex] present in 1 mole of a substance.

Mathematically, 1 mole = [tex]6.022 \times 10^{23}[/tex] atoms or molecules

Therefore, calculate the number of carbon atoms present in 0.1 mol of [tex]C_{2}H_{4}[/tex] as follows.

[tex]2 \times 0.1 mol \times 6.022 \times 10^{23}}atoms /mol[/tex]

= [tex]1.204 \times 10^{23}[/tex] atoms

Thus, we can conclude that **there are [tex]1.204 \times 10^{23}[/tex] atoms of carbon atoms present in 0.1 mol of [tex]C_{2}H_{4}[/tex].**