Correct order of basic strength of Pyrrole , Pyridine and Piperidine is :

For the given compounds, the correct order of increasing $$\mathrm{pK}_{\mathrm{a}}$$ value :

Choose the correct answer from the options given below :

Methods used for purification of organic compounds are based on :

The correct sequence of acidic strength of the following aliphatic acids in their decreasing order is:

$$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}, \mathrm{CH}_3 \mathrm{COOH}, \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{COOH}, \mathrm{HCOOH}$$