JEE Main 35 Year PYQs- Carbohydrates, Amino Acids, Polymers & Miscellaneous

Polymerisation starts either by conden sation or addition reactions between monomers. Condensation polymers are formed by the combination of monomers with the elimination of simple molecules.Where as the addition polymers are formed by the addition together of the molecules of the monomer or monomers to form a large molecule without elimination of any thing.

In RNA, the sugar is D–ribose and base is uracil where as in DNA, the sugar is D-2 de oxyribose and the nitrogenous base is thymine.

The given compound is aspirin which is antipyretic and analgesic

Liquid hydrogen and liquid oxygen are used as excellent fuel for rockets. H₂(ℓ) has low mass and high enthalpy of combustion whereas oxygen is a strong supporter of combustion.

Nylon is a polyamide polmer.

Cellulose is a linear polymer of β –D– glucose in which C₁ of one glucose unit is connected to C₄ of the other through β–D glucosidic linkage. It does not undergo hydrolysis easily. However on heating with dilute H₂SO₄ under pressure. It does undergo hydrolysis to give only D– glucose.

DNA consists of two polynucleotide chains, each chain forms a right handed spiral with ten bases in one turn of the spiral. The two chains coil to double helix and run in opposite direction held together by hydrogen bonding.

RNA contains cytosine and uracil as pyrimidine bases while DNA has cytosine and thymine.
Both have the same purine bases i.e., Guanine and adenine.

Insulin is a hormone.  It's a chemical substance that regulates the activity of organs and cells. Insulin is secreted by the pancreas and helps maintain blood glucose levels.  Insulin also allows glucose from the blood to enter cells, which provides them with energy. 

 Photochemical smog is caused by oxides of sulphur and nitrogen.

Nylon-66 is a polyamide of hexamethylene diamine (CH2)6(NH2)2 and adipic acid (CH2)4(COOH)2.

An antipyretic is a drug which is responsible for lowering the temperature of the feverish organism to normal but has  no effect on normal temperature states

In DNA and RNA heterocyclic base and phosphate ester are at C₁' and C₅' respectively of the sugar molecule.

Teflon is polymer of CF₂ = CF₂.

Cyclization of th e open ch ain str ucture of D-(+)-glucose has created a new stereocenter at C₁ which explains the existence of two cyclic forms of D-(+)-glucose, namely α– and β–. These two cyclic forms are diasteromers, such diastereomers which differ only in the configuration of chiral carbon developed on hemiacetal formation (it is C₁ in glucose and C₂ in fructose) are called anomers and the hemiacetal carbon (C₁ or C₂) is called the anomeric carbon.

The pyrimidine bases present in DNA are cytosine and thymine.

The secondary structure of a protein refers to the shape in which a long peptide chain can exist. There are two different conformations of the peptide linkage present in protein, these are α-helix and β-conformation. The α-helix always has a right handed arrangement. In β-conformation all peptide chains are streched out to nearly maximum extension and then laid side by side and held together by intermolecular hydrogen bonds.
The structure resembles the pleated folds of drapery and therefore is known as β-pleated sheet.

NOTE : Ozone layer acts as a shield and does not allow ultraviolet radiation from sun to reach earth. It does not prevent infra-red radiation from sun to reach earth.
Thus option (c) is wrong statement and so it is the correct answer.

Bakelite is formed by the reaction of formaldehyde (HCHO) and phenol so the correct answer is (d).

Since α - D - (+)- glucose and β - D - (+) glucose differ in configuration at C – 1 atom so they are anomers.
NOTE : Anomers are those diastereomers that differ in configuration at C – 1 atom. i.e.,  (c) in the correct answer.

The cross linked polymers will be formed by RSiCl₃

The correct choice is (c)

Buna – N is a copolymer of butadiene (CH₂ = CH – CH = CH₂) and acrylonitrile (CH₂ = CHCN).

NOTE : Glucose is considered as a typical carbohydrate which contains –CHO and –OH group.

Biuret test produces violet colour on addition of dilute CaSO₄ to alkaline solution of a compound containing peptide linkage.
Polypeptides, proteins and urea have  (peptide) linkage while carbohydrates have glycosidic llinkages. So, test of carbohydtrates should be different from that of other three.

Nylon 6-6 has amide lin kage capable of forming hydrogen bon ding.

RNA has D (–) - Ribose and the DNA has 2–Deoxy D (–) – ribose as the carbohydrate unit.

From the structures it is clear that 2^nd carbon in DNA do not have OH group.

Molisch's Test : This is a general test for carbohydrates.
One or two drops of alcoholic solution of a-naphthol is added to 2 ml glucose solution. 1 ml of conc. H₂SO₄ solution is added carefully along the sides of the testtube. The formation of a violet ring at the junction of two liquids confirms the presence of a carbohydrate or sugar.

Lewis acids are the most common compounds used for initiation of cationic polymerisation. The more popular Lewis acids are SnCl₄, AlCl₃, BF₃ and TiCl₄.

With the exception of glycine all the 19 other common amino acids have a uniquely different functional group on the central tetrahedral alpha carbon.