Secondary structure of proteins involves α-helical back bond and β-sheet structures. These structures are formed as a result of H-bonding between different peptide groups. Hence, (A) is correct
The secondary structure of a protein refers to
Held on 30 Apr 2007 · Verified 6 Jul 2026.
α-helical backbone
hydrophobic interactions
sequence of α-amino acids
fixed configuration of the polypeptide backbone
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Consider the following reaction sequence  Compound $(\mathrm{y})$ develops characteristic colour with neutral $\mathrm{FeCl}_{3}$ solution. Identify the INCORRECT statement from the following for the above sequence.
Given below are two statements: Statement I: Benzene is nitrated to give nitrobenzene, which on further treatment with $\mathrm{CH}_{3} \mathrm{COCl} / \mathrm{AlCl}_{3}$ will give  Statement II: $-\mathrm{NO}_{2}$ group is a $m$-directing, and deactivating group. In the light of the above statements, choose the most appropriate answer from the options given below
Given below are two statements: Statement I: $\left(\mathrm{CH}_{3}\right)_{3} \stackrel{\oplus}{\mathrm{C}}$ is more stable than $\stackrel{\oplus}{\mathrm{C}} \mathrm{H}_{3}$ as nine hyperconjugation interactions are possible in $\left(\mathrm{CH}_{3}\right)_{3} \stackrel{\oplus}{\mathrm{C}}$. Statement II: $\stackrel{\oplus}{\mathrm{C}} \mathrm{H}_{3}$ is less stable than $\left(\mathrm{CH}_{3}\right)_{3} \stackrel{\oplus}{\mathrm{C}}$ as only three hyperconjugation interactions are possible in $\stackrel{\oplus}{\mathrm{C}} \mathrm{H}_{3}$. In the light of the above statements, choose the correct answer from the options given below
Which of the following reactions is an example of Wurtz reaction?
A hydroxy compound $(\mathrm{X})$ with molar mass $122 \mathrm{~g} \mathrm{~mol}^{-1}$ is acetylated with acetic anhydride, using a large excess of the reagent ensuring complete acetylation of all hydroxyl groups. The product obtained has a molar mass of $290 \mathrm{~g} \mathrm{~mol}^{-1}$. The number of hydroxyl groups present in compound (X) is:
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