Question

Phosphorus-32, a radioactive isotope of phosphorus-31 (atomic number 15), undergoes a form of radioactive decay whereby a neutron turns into a proton, which is retained in the nucleus and emits radiation in the form of an electron. What is the product of such radioactive decay of phosphorus-32?
a. a negatively charged phosphorus-32 ion.
b. a positively charged phosphorus-31 ion.
c. sulfur-32 (atomic number 16).
d. phosphorus-31.
e. the conversion of the phosphorus-32 atom into pure energy.

Answer 1

Answer: c. sulfur-32 (atomic number 16).

Explanation:

$\beta ^-$-decay is a type of decay process, in which a proton gets converted to neutron and an electron. In this the mass number remains same but the atomic number is increased by 1.

For the given fission reaction:

$^{32}_{15}\textrm{P}\rightarrow ^A_Z\textrm{X}+^{0}_{-1}\textrm{e^-}$

To calculate A:

Total mass on reactant side = total mass on product side

32  = A + 0

A = 32

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

15  = Z - 1

Z = 16

The isotopic symbol of the product will be$_{16}^{32}\textrm{S}$