Chemistry: CUET Mock Test - 8 - CUET MCQ

Hyponitric acid is not a recognized oxo-acid of nitrogen and does not exist in standard chemical nomenclature. The other three options—hyponitrous acid (H₂N₂O₂, structure HON=NOH), nitrous acid (HNO₂, formed in the atmosphere and unstable), and nitric acid (HNO₃)—are well-known oxo-acids of nitrogen.

Aldol condensation requires an aldehyde or ketone with at least one alpha hydrogen.

• Methanal (formaldehyde, HCHO) lacks alpha hydrogens and cannot undergo Aldol condensation.
• Benzaldehyde (C₆H₅CHO) also lacks alpha hydrogens due to the absence of an alpha carbon with hydrogen.
• 2,2-Dimethylbutanal ((CH₃)₂C(CH₂CH₃)CHO) has no alpha hydrogens because the alpha carbon is quaternary.
• Phenylacetaldehyde (C₆H₅CH₂CHO) has two alpha hydrogens and can form an enolate, enabling Aldol condensation to produce an alpha-beta unsaturated aldehyde. Therefore, only phenylacetaldehyde undergoes Aldol condensation.

A. Analgesics reduce or abolish pain without causing impairment of consciousness, or mental confusion.
This statement is true. Analgesics are drugs that are used to reduce or relieve pain, but they do not cause impairment of consciousness or mental confusion. They work by blocking the transmission of pain signals to the brain.
B. Tranquilizers are neurological inactive drugs.
This statement is false. Tranquilizers, also known as sedatives, are drugs that depress the central nervous system and can cause drowsiness and relaxation. They are used to treat anxiety, insomnia, and other conditions.
C. Morphine is an example of a non-narcotic analgesic.
This statement is false. Morphine is a narcotic analgesic, which means it is a drug that is used to relieve pain and can also cause sedation, respiratory depression, and euphoria. Narcotic analgesics are also known as opioids.
D. Disinfectants are applied to inanimate objects whereas antiseptics are applied to living tissues.
This statement is true. Disinfectants are substances that are used to kill or eliminate microorganisms on inanimate objects, such as floors, walls, and equipment. Antiseptics, on the other hand, are substances that are used to kill or eliminate microorganisms on living tissues, such as skin and mucous membranes.
E. Same substance can act as an antiseptic as well as a disinfectant by varying the concentration.
This statement is true. Many substances, such as alcohol and hydrogen peroxide, can act as both antiseptics and disinfectants depending on their concentration. A higher concentration of these substances can be used as a disinfectant on inanimate objects, while a lower concentration can be used as an antiseptic on living tissues.
Therefore, the correct answer is Option 1: A, D, and E only.
Tranquilizers are neurologically active drugs. Morphine is an example of narcotic analgesic.

Alitame is an artificial sweetener that is approximately 2000 times sweeter than cane sugar (sucrose). It is a low-calorie sweetener that is commonly used in a variety of food and beverage products.

→ Glyptal is a copolymer made from the condensation reaction between ethylene glycol and phthalic anhydride.
→ A copolymer is a polymer made up of two or more different types of monomers. In the case of glyptal, the two different monomers are ethylene glycol and phthalic anhydride.
A copolymer is formed by the polymerisation reaction in which a mixture of more than one monomeric species is allowed to polymerise.

→ Maltose is a disaccharide made up of two glucose molecules linked together through a glycosidic bond formed by the condensation reaction between the anomeric carbon atom of one glucose molecule and the hydroxyl group of another glucose molecule.
The other options are:
→ Glucose is a monosaccharide, also known as a simple sugar, which means it is a single sugar molecule. It is the primary source of energy for the body and is used in the production of many important molecules, such as ATP, glycogen, and starch.
→ Glycogen is a polysaccharide, which means it is made up of many glucose molecules linked together. It is the main storage form of glucose in animals and is stored in the liver and muscles.
→ Starch is also a polysaccharide and is the primary storage form of glucose in plants. It is made up of two types of glucose molecules: amylose and amylopectin. Amylose is a linear chain of glucose molecules, while amylopectin is a branched chain of glucose molecules.
→ In summary, maltose is a disaccharide, made up of two glucose molecules linked together, while glucose is a monosaccharide, glycogen and starch are polysaccharides.
Disaccharides are formed by the glycosidic linkage of two monosaccharide units.
Maltose is a disaccharide which is composed of two a-D-glucose units.

Structure of ribose & deoxyribose:

→ When the sugar molecule is drawn in Fischer projection and the most oxidised carbon atom is at the top and the hydroxyl (−OH) on the bottom chiral centre points to the right side then it is known as D-sugar.
→ We know, ribose and deoxyribose sugars are D-sugars.
→ We know that if a molecule cannot be superimposed on its mirror image by any combination of rotations or translations then the molecule is said to be chiral. Thus, the RNA and DNA molecules are chiral because of the sugar molecules.
→ Thus, RNA and DNA are chiral molecules, their chirality is due to D-sugar components.

DNA nucleotides contain one of four nucleobases: cytosine (C), guanine (G), adenine (A), or thymine (T). Uracil (U) is found in RNA, not DNA. Therefore, the nucleobases in DNA are cytosine, guanine, adenine, and thymine (Option C).

Polymerization is a reaction in which two or more monomers combine to form a polymer, often via addition or condensation mechanisms. Therefore, the correct answer is A.

Rancidity is the oxidation of oils or fats in food, leading to changes in smell and taste. Therefore, the correct answer is B.

Synthetic detergents differ from soaps in several ways:

• A: Correct. Synthetic detergents have similar cleansing properties to soaps.
• B: Correct. Detergents produce foam in both soft and hard water, unlike soaps, which form scum in hard water.
• C: Incorrect. Synthetic detergents can be used in acidic media, while soaps precipitate due to protonation of carboxylate groups.
• D: Correct. Many detergents, especially non-ionic ones, are derived from vegetable oils. Therefore, option C is NOT correct.

Phenols are differentiated from alcohols by the presence of the hydroxyl group attached to an aromatic ring, whereas alcohols have the hydroxyl group attached to a saturated carbon atom.

Glycerol is an example of a polyhydric alcohol as it contains three hydroxyl groups in its structure, while other options have only one.

B: Presence of an aromatic ring

Explanation:

Phenols are more acidic than alcohols due to:

1. Stabilization of the Phenoxide Ion:

   • When phenol loses a proton (H⁺), it forms a phenoxide ion (C₆H₅O⁻).

   • The aromatic ring delocalizes the negative charge through resonance, stabilizing the phenoxide ion.

2. Electron-Withdrawing Effect of the Aromatic Ring:

   • The sp²-hybridized carbon in the benzene ring withdraws electron density from the oxygen, making the O–H bond more polar and acidic.

3. Comparison with Alcohols:

   • In alcohols (e.g., ethanol, C₂H₅OH), the alkoxide ion (RO⁻) is not resonance-stabilized, making alcohols less acidic.

Why Other Options Are Incorrect:

• A: The hydroxyl group itself is electron-donating, not withdrawing.

• C: Hydrogen bonding affects solubility/boiling points, not acidity.

• D: Hybridization matters (sp² in phenol vs. sp³ in alcohols), but the key factor is resonance stabilization, not hybridization alone.

When a Grignard reagent (RMgX) reacts with an aldehyde, the nucleophilic alkyl group (R) from the Grignard reagent attacks the carbonyl carbon of the aldehyde, leading to the formation of a secondary alcohol after hydrolysis. This is because aldehydes have one alkyl group and one hydrogen attached to the carbonyl carbon, so the product will be a secondary alcohol.

Phenols are prepared from haloarenes (e.g., chlorobenzene) by reacting with sodium hydroxide at high temperature (350°C) and pressure (300 atm), followed by acidification. This process, known as Dow’s process, involves nucleophilic aromatic substitution, where the halide is replaced by a hydroxyl group: C₆H₅Cl + NaOH → C₆H₅OH + NaCl (after H⁺).

• A: Incorrect. Hydroboration-oxidation is used for alkenes to form alcohols.
• B: Incorrect. Acid-catalyzed hydration is for alkenes, not haloarenes.
• C: Correct. Reaction with NaOH under harsh conditions produces phenols.
• D: Incorrect. Grignard reagents are not used for this transformation. Therefore, option C is correct.

Ethanol is prepared primarily through fermentation of sugars, whereas methanol is prepared by catalytic hydrogenation of carbon monoxide.

Ethanol is widely used as a solvent in industries like pharmaceuticals, cosmetics, and chemicals due to its ability to dissolve both polar and non-polar compounds. It is also used as a fuel (e.g., biofuel), preservative, and in beverages, but the passage highlights its solvent role in industrial contexts. Therefore, option B is correct:

• A: Incorrect. Fuel is significant but not highlighted as the main use in the passage.
• B: Correct. Solvent is a primary industrial use.
• C: Incorrect. Preservative is a minor use.
• D: Incorrect. Ethanol is not used as a catalyst.

Methanol is toxic because it is metabolized to formaldehyde and formic acid in the body, which are harmful and can cause blindness or death.

Zymase is the enzyme responsible for the fermentation of sugars, which produces ethanol.

If air gets into the fermentation mixture, ethanol is oxidized to acetic acid, which destroys the taste of alcoholic beverages.

• A: Correct. Transition metals are good conductors of heat and electricity due to delocalized electrons.
• B: Correct. Transition metals form complex compounds, many of which are used in industrial catalysis (e.g., Fe in Haber process).
• C: Correct. The first transition series elements show gradual changes in properties (e.g., atomic radius decreases, electronegativity increases) due to increasing nuclear charge.
• D: Correct. The properties of d-block elements are influenced by the small energy gap between 3d and 4s orbitals, affecting electron configurations and oxidation states. Therefore, the correct answer is A, B, C, and D.

(A) is incorrect because the first transition series typically has varying electron configurations with some having one or two electrons in the s-orbitals.
(B) is correct as transition metals like iron and copper are widely used in alloys like steel due to their strength and malleability.
(C) is incorrect since not all transition metals have a +2 oxidation state; they exhibit a range of oxidation states depending on the element.
(D) is correct as transition metals exhibit multiple oxidation states due to the involvement of both s and d electrons in bonding.

The laboratory preparation of nitric acid involves heating sodium nitrate (NaNO₃) with concentrated sulfuric acid (H₂SO₄) in a glass retort, producing nitric acid (HNO₃) and sodium hydrogen sulfate (NaHSO₄):

• C: NaNO₃ + H₂SO₄ → NaHSO₄ + HNO₃ (correct for lab scale).
• A: 3HNO₂ → HNO₃ + H₂O + 2NO represents nitrous acid decomposition, not a practical lab method.
• B: NO₂ + O₂ → NO₃ is chemically incorrect and not relevant.
• D: 3NO₂ + H₂O → 2HNO₃ + NO is part of the Ostwald process (industrial), not lab scale. Therefore, option C is correct.

In Ostwald’s process for nitric acid production, platinum-rhodium (Pt-Rh) gauze is used as a catalyst for the oxidation of ammonia to nitric oxide. Other options are incorrect:

• A: Fe₂O₃ is used in the Haber process (ammonia synthesis).
• B: V₂O₅ is used in the contact process (sulfuric acid production).
• C: Zn-Hg is used in Clemmensen reduction. Therefore, option D is correct.

1 mole of sulfur, S₈ requires 48 moles of concentrated nitric acid. The reaction is given by S₈ + 48HNO₃ → 8H₂SO₄ + 48NO₂ + 16H₂O. 10, 4 and 20 moles of concentrated nitric acid is required to produce iodic acid, carbon dioxide and phosphoric acid from 1 mole of iodine, carbon and phosphorus, respectively.

Aluminum does not dissolve in nitric acid. This is because treatment with nitric acid results in the formation of a tough oxide layer. This oxide layer prevents it from further reacting with the oxide. Hence, the compound formed is Al₂O₃ i.e. aluminum (III) oxide.

Experimentally, it is determined that nitric acid and water form a constant boiling azeotrope at 68% – 32% by mass composition, respectively. Here, it becomes impossible to separate water and nitric acid by distillation methods. Thus, concentrated sulfuric acid is used for dehydration and removal of water.

Ostwald’s process is the industrial method for manufacturing nitric acid by oxidizing ammonia to nitric oxide, then nitrogen dioxide, and dissolving it in water to form HNO₃. Other options are incorrect:

• A: Contact process produces sulfuric acid.
• B: Haber-Bosch produces ammonia.
• C: Solvay produces sodium carbonate. Therefore, option D is correct.

Nitric acid (HNO₃) is a monobasic acid, meaning it donates one proton per molecule (basicity = 1).

• A: Incorrect. Nitric acid is a strong oxidizing agent, not a reducing agent.
• B: Correct. Nitric acid is monobasic.
• C: Incorrect. Nitric acid is a strong oxidizing agent.
• D: Incorrect. Nitric acid is planar in the gaseous state due to sp² hybridization of the nitrogen atom. Therefore, option B is correct.