Question

question 17 of 25
which nucleus completes the following equation?
$_{17}^{39}cl\
ightarrow _{ - 1}^{0}e+?$
a. $_{18}^{39}y$
b. $_{16}^{39}sr$
c. $_{18}^{39}ar$
d. $_{16}^{39}s$

Explanation:

Step1: Apply conservation of mass - number

In a nuclear reaction, the sum of mass - numbers on the left - hand side must equal the sum of mass - numbers on the right - hand side. The mass - number of $^{39}_{17}Cl$ is 39 and the mass - number of $^{0}_{- 1}e$ is 0. Let the mass - number of the unknown nucleus be $A$. So, $39=0 + A$, which gives $A = 39$.

Step2: Apply conservation of atomic number

The sum of atomic numbers on the left - hand side must equal the sum of atomic numbers on the right - hand side. The atomic number of $^{39}_{17}Cl$ is 17 and the atomic number of $^{0}_{-1}e$ is - 1. Let the atomic number of the unknown nucleus be $Z$. So, $17=-1 + Z$, which gives $Z = 18$.

Step3: Identify the element

The element with atomic number $Z = 18$ is argon (Ar). The nucleus is $^{39}_{18}Ar$.

Answer:

C. $^{39}_{18}Ar$