Step-by-step explanation:
Adding a neutron will not affect the charge. The atom remains neutrally charged.
Since the charge of a neutron is neutral, or 0, the charge is not affected. Protons have a positive charge, whereas electrons have a negative charge. Since there are an equal number of protons and electrons, they cancel out.
Adding a neutron also increases the mass by 1. The mass of a neutron is 1 amu. The atomic mass is calculated by protons + neutrons.
Originally, the mass is 7 (because 3+4). The mass would now be 8 (because 3+5).