Question

An atom has 3 protons and 4 neutrons ?What is its atomic number and mass number

Answer 1

A lithium atom contains 3 protons in its nucleus irrespective of the number of neutrons or electrons. Notice that because the lithium atom always has 3 protons, the atomic number for lithium is always 3. The mass number, however, is 6 in the isotope with 3 neutrons, and 7 in the isotope with 4 neutrons.

Answer 2

the atomic number of this atom is 3

And mass number is 7