During β emission the parent and daughter nuclei will be:

isobars

Reason — During emission of a β-particle, the number of nucleons in the nucleus (i.e., sum of protons and neutrons) remains the same, but the number of neutrons is decreased by one and the number of protons is increased by one i.e., the mass number A does not change, but the atomic number Z is increased by one. Therefore the parent and daughter nuclei have the same mass number but different atomic numbers. Hence, they form isobars.