The number of protons in the nucleus of a carbon atom is ______.

For neutral atom of element number of protons is equal to number of electrons.

$\text{Number\hspace{0.17em}of\hspace{0.17em}protons}=\text{Number\hspace{0.17em}of\hspace{0.17em}electron}=\text{Atomic\hspace{0.17em}number}$

For carbon atom atomic number $\text{Z}=6$ . So number of protons present in the nucleus of carbon atom is 6.