What is the mass number of an atom with 3 protons 4 neutrons and 3 electrons?

The mass number of an atom is the total number of protons and neutrons in the nucleus of an atom.

In this case, the atom has 3 protons and 4 neutrons, giving a total of 7 nucleons (protons + neutrons).

The mass number of this atom would be 7.

The number of electrons (3) does not affect the mass number, as electrons have a negligible mass compared to protons and neutrons.