Answer : The compound that would be most soluble in water is CH3CH2CH2OH
Explanation :
Water is a polar solvent and can dissolve polar molecules. This is based on the principle "Like dissolves like".
Among the given molecules, CH3CH2CH2CH3 is a hydrocarbon known as butane. All hydrocarbons are non polar. Therefore this compound will not be soluble in water.
The remaining compounds are polar, but Ch3CH2CH2OH shows greater solubility in water owing to presence of hydrogen bonding.
Hydrogen bonding is a type of intermolecular force that gets formed when a compound has hydrogen atom directly attached to highly electro-negative N, F or O atom.
When CH3CH2CH2OH is dissolved in water, it forms hydrogen bonds with water molecules. Due to this hydrogen bonding, the molecule shows greater solubility.
Therefore CH3CH2CH2OH is the most soluble compound in water
<u>Answer:</u> The volume of HBr solution required is 130.16 mL
<u>Explanation:</u>
To calculate the concentration of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is 
We are given:

Putting values in above equation, we get:

Hence, the volume of KOH solution required is 130.16 mL
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 :
