Which of the following is regarded as the principal functional group ?

As per IUPAC rules, which one of the following groups, will be regarded as the principal functional group?

Which of the following violates the Aufbau principal ?

Which of the following is not regarded as a pollutant ?

Which of the following is not true regarding a rational function?

Which of the following is a correct priority order of functional groups ?

Which of the following is incorrect priority order of functional groups ?

Which of the following is not a principal lymphod organ?

In which of the following compounds -OH is the functional group ?

which of the following compounds contain (s) -CHO as the functional group ?