Which among the given acids has the lowest $pKa$ value?

Two statements are given below:
Statement $I:$ The melting point of monocarboxylic acids with an even number of carbon atoms is higher than that of acids with an odd number of carbon atoms immediately below and above it in the series.
Statement $II:$ The solubility of monocarboxylic acids in water decreases with an increase in molar mass.
Choose the most appropriate option.

Describe the colours,smell,and physical state of aliphatic carboxylic acids.

Which of the following derivatives of alcohols is unstable in an aqueous base $?$

The most suitable reagent for the given conversion is

Identify $P$ and $Q$ in the above reaction respectively.