How many protons, electrons, and neutrons does an atom with atomic number of 47 and mass number of 108?

An atom contains protons, neutrons and electrons. 

The atomic number of an atom equals to the number of protons of that atom, therefore, the number of protons for this atom is 47.

The mass number of an atom equals the sum of protons and neutrons, but not electron, as they're too light. Therefore, to calculate the number of neutrons for this atom, we can subtract the number of protons (which is 47) from the mass number. 108 - 47 = 61. So the number of neutrons is 61.

And for the number of electrons of an atom, it should be the same as the number of protons, or else, it would be an ion instead of an atom. So, the number of electrons for this atom is 47. 

In conclusion, the answers are protons:47, electrons:47, neutrons:61

The answer is c. 320 g