Question

No of proton in 6.02X10²³ atom of carbon

Answer 1

All atoms of carbon have 6 protons in their nucleus - that’s the definition of carbon.

The number you quote is Avagadro’s number/constant. This is the number of particles in one mole of those particles, and is the same for all atoms, molecules, nuclei and ions. It is defined as the mass, expressed in grams, of the atomic mass of a particle of the material being considered, in atomic mass units, amu’s. I amu is defined as 1/12th of a C-12 atom. So, 12 g of C-12 has exactly 6.023 X 10^23 atoms.

There are several ways of measuring Avagadro’s constant, and they are worth looking up