Nuclear Physics and RadioactivityHard
Question
A radioactive nucleus (initial mass number A and atomic number Z) emits 3 α - particles and 2 positrons. The ratio of number of neutrons to that of protons in the final nucleus will be
Options
A.

B.

C.

D.

Solution
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.
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.
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