What isotopes has seven neutrons is it boron-12 or nitrogen-12 or hydrogen-12 or carbon-14?

Carbon-14 has seven neutrons. The atomic number of carbon is 6, which means it has 6 protons, and since carbon-14 has a mass number of 14, it has 14 - 6 = 8 neutrons. Therefore, none of the isotopes listed have exactly seven neutrons.