The number of hours required : 37.2 hours
<h3>Further explanation</h3>
Given
⁴²K (potassium -42)
Required
The number of hours
Solution
The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually, radioactive elements have an unstable atomic nucleus.
Based on Table N(attached), the half-life for ⁴²K is 12.4 hours, which means half of a sample of ⁴²K will decay in 12.4 hours
For three half-life periods :

It is the gravitational force pulling on something
Mass no. = Protons + Neutrons
Mass no.= 6 + 8
= 14
If you look at the periodic table, you will see that the carbon atom has a mass number of 12. But if you compare with this carbon, it is 14. This is because this carbon atom is an isotope. The isotope is called carbon-14.