Once <u>hydrogen</u> bonds form between every fourth amino acid in a polypeptide chain, the chain begins to twist into the <u>secondary</u> structure known as a(n) <u>alpha helix</u>.
<h3>
What is Amino Acid ? </h3>
Amino acids are organic compound. Amino acids contains amine and carboxyl functional group. Amino acids is the building block of life these are the molecules that combine to form proteins.
<h3>What is Polypeptide Chain ? </h3>
A unique sequence of amino acids joined by peptide bonds is called polypeptide.
Thus from the above conclusion we can say that Once <u>hydrogen</u> bonds form between every fourth amino acid in a polypeptide chain, the chain begins to twist into the <u>secondary</u> structure known as a(n) <u>alpha helix</u>.
Learn more about the Amino acids here: brainly.com/question/2526971
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Answer: The correct option is 2.
Explanation: Group 15 elements are Nitrogen, phosphorous, Arsenic, Antimony, Bismuth.
To know whether an element exits as a diatomic molecule or not, we look at the atomicity of an element.
Atomicity is the number of atoms of an element combining to form a molecule.
Atomicity of Nitrogen = 2
Atomicity of Phosphorous = 4
Atomicity of Bismuth = 1
Atomicity of Arsenic = 1
The element having atomicity 2 will exist as a diatomic molecule.
Hence, Nitrogen is a diatomic molecule 
Answer:
From the Online Catalog to the Shelf
Libraries in the United States generally use either the Library of Congress Classification System (LC) or the Dewey Decimal Classification System to organize their books. Most academic libraries use LC, and most public libraries and K-12 school libraries use Dewey.
Explanation:
