Answer 1

The H-bonds formed between the −NH group of each amino acid residue and the  group of the adjacent turns of the ∝-helix help in stabilising the helix.

Answer 2

The α-helix structure of proteins is stabilized by intramolecular H-bonding between C = O of one amino acid residue and the N – H of the fourth amino acid residue in the chain. This causes the polypeptide chain to coil up into a spiral structure called right handed α- helix structure.