How many polypeptide chains are present in the structure of hemoglobin?

Which of the following compounds shows aromatic properties?

Which of the following amino acids is basic in nature?

Which of the following tests is not used for testing of proteins?

What is the polypeptide chain composition of adult hemoglobin $(Hb)$?

Statement $P$: The quaternary structure of proteins is either globular or fibrous.
Statement $Q$: The three-dimensional arrangement of molecules consisting of a single polypeptide chain is the quaternary structure of proteins.