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 :

Lead (II) acetate trihydrate is the systematic name for the formula Pb(C₂H₃O₂)₂ . 3H₂O.
<h3>What is Molecular Formula ?</h3>
The chemical formula that gives total number of atoms of each element in one molecule of a compound is called Molecular Formula.
<h3>What is Oxidation State ?</h3>
Oxidation state is also known as oxidation number. It is defined as the atom is equal to the total number of electrons which have been removed from the element in order to form chemical bond with other atom.
Now find the oxidation state of Pb in Pb(C₂H₃O₂)₂ .3H₂O
Assume the oxidation state of Pb in Pb(C₂H₃O₂)₂ .3H₂O be x
x + 2 × (-1) + 3 × 0 = 0
x - 2 + 0 = 0
x = 2
Oxidation state of Pb is +2 or (II)
Thus from the above conclusion we can say that The systematic name for the formula Pb(C₂H₃O₂)₂ .3H₂O is Lead (II) acetate trihydrate.
Learn more about the Molecular Formula here: brainly.com/question/15960587
#SPJ4