What type of protein structure is shown in the given figure?

What is the full name of the chemical group represented by $NH_{2}$?

Which of the following statement$(s)$ is/are true?
$(i)$ All amino acids contain one chiral centre.
$(ii)$ Some amino acids contain one, while some contain more chiral centres or even no chiral centre.
$(iii)$ All amino acids in proteins have $L$-configuration.
$(iv)$ All amino acids found in proteins have $1^{\circ}$ amino group.

Hemoglobin is a type of ............ .

The antibodies in our body are complex $ \dots $.

Protein can be most easily removed by: