In positive beta decay a proton is transformed into a neutron and a positron is emitted p+ → n0 + e+ no. of neutrons initially was A − Z no. of neutrons after decay (A − Z) − 3 × 2 (due to alpha particles) + 2 × 1 (due to positive beta decay) The no. of proton will reduce by 8. [as 3 × 2 (due to alpha particles) + 2 (due to positive beta decay)] Hence atomic number reduces by 8.