bantuk kak soal SMA kimia tentukan jumlah proton neutron dan elektron

1. proton = 20, elektron = 20, neutron = 20
2. proton = 19, elektron = 18, neutron = 20
3. proton = 8, elektron = 10, neutron = 8
4. proton = 15, elektron = 15, neutron = 16