VITEEE Chemistry Test - 1 - JEE MCQ

Ethyl alcohol on controlled oxidation with acidified K₂Cr₂O₇ gives acetaldehyde (ethanal) as the primary product. Upon further oxidation, it can be converted to acetic acid (ethanoic acid). Therefore, the immediate product of controlled oxidation is acetaldehyde.

Ammonia (NH₃) reacts differently with the given compounds:

• HCHO (Formaldehyde): Ammonia reacts with formaldehyde to form hexamethylenetetramine, a reaction not typical with the other ketones or aldehydes.
• CH₃CHO (Acetaldehyde) and CH₃COCH₃ (Acetone): These react with ammonia to form enamine derivatives or imine derivativ es under specific conditions, differing from the reaction with formaldehyde.

Thus, NH₃ (D) is the reagent that reacts differently with HCHO compared to the other compounds.

• The Wurtz reaction is a coupling reaction used to synthesize alkanes.
• It involves the treatment of alkyl halides with sodium metal in anhydrous (dry) ether.
• The sodium metal acts as a reducing agent, facilitating the removal of halogen atoms and the formation of a new carbon-carbon bond between the alkyl groups.
• This reaction is particularly useful for forming symmetrical alkanes from identical alkyl halides.

Therefore, the correct answer is A: Sodium.

1-Butene is an alkene, and to convert it to butane (an alkane), it requires hydrogenation, which is the addition of hydrogen across the double bond.

• Pd/H₂ (palladium on hydrogen) is a catalyst used for hydrogenation reactions. When 1-butene reacts with Pd/H₂, the hydrogen atoms add to the carbon-carbon double bond, resulting in the formation of butane.

Other options:

• Zn-HCl and Sn-HCl are used for reducing compounds but do not specifically hydrogenate alkenes to alkanes.
• Zn-Hg is used in Clemmensen reduction, which reduces carbonyl groups, not alkenes.

Thus, the correct answer is Option D: Pd/H₂.

The correct answer is Metalloid.

• Silicon (Si) is a metalloid chemical element in the carbon family (Group 14 [IVa] of the periodic table). 
• When decontaminated, it is a greyish crystal that looks metallic but it is not.

Key Points:

• Silicon is the second most abundant element in the crust, after Oxygen, and makes up 27.7% of Earth’s crust and is present in nature in the form of silica and silicates.
• Silicon dioxide, commonly known as silica, occurs in several crystallographic forms.
• Pure silicon is too reactive to be found in nature, but it is found in practically all rocks as well as in sand, clays, and soils, combined either with oxygen as silica (SiO₂, silicon dioxide) or with oxygen and other elements like aluminium, magnesium, calcium, sodium, potassium, or iron as silicates. 
• Quartz, cristobalite, and tridymite are some of the crystalline forms of silica, and they are interconvertible at a suitable temperature.
• Silicon is a very important component of ceramics, glass and cement.

 Insulin is the protein responsible for maintaining blood sugar levels.

•  It is a hormone produced by the pancreas.
•  Insulin regulates glucose levels by facilitating the uptake of glucose into cells.
•  It helps store glucose as glycogen in the liver and muscles.
•  When blood sugar levels rise, insulin is released to lower them.
•  Insufficient insulin production or action leads to diabetes.
• Other options like haemoglobin, oxytocin, and ptyalin have different functions unrelated to blood sugar regulation.

Therefore,Correct Answer- Option C

Option A: Starch is a polymer of α-glucose, not β-glucose. Amylose and amylopectin are the two components of starch, both comprising α-glucose units.
Option B: Amylose is a component of starch, not cellulose. Cellulose is made of β-glucose units.
Option C: Proteins are composed of 20 different amino acids, not just one type.
Option D: In fructose's cyclic structure (a furanose form), there are four carbons and one oxygen in the ring, making this statement correct.
Thus, the correct answer is Option D.

A nutrient that the body needs in small amounts to stay healthy and work the way it should. It is fat-soluble (can dissolve in fats and oils) and is found in seeds, nuts, leafy green vegetables, and vegetable oils. Alpha-tocopherol boosts the immune system and helps keep blood clots from forming.

Hence A and C

Dimerisation in carboxylic acids occurs due to:

• Intermolecular Hydrogen Bonding: Carboxylic acids have a carboxyl group (-COOH) that can form hydrogen bonds.
• Each molecule forms two hydrogen bonds with another, creating a dimer.
• This dimerisation happens because the hydrogen of one -OH group forms a bond with the oxygen of another molecule’s carbonyl group.
• This interaction stabilizes the structure and is responsible for increased boiling points.

Fehling's solution is a chemical reagent used to test for the presence of reducing sugars and aldehydes. It contains copper(II) ions, which are reduced to copper(I) oxide (a red precipitate) in the presence of reducing agents.

Let’s analyze the options:

Option A: C₆H₅COOH (Benzoic acid): Benzoic acid is a carboxylic acid, and carboxylic acids are generally not reducing agents, so it does not react with Fehling's solution.

Option B: HCOOH (Formic acid): Formic acid is an aldehyde, and aldehydes are known to react with Fehling’s solution. It reduces the copper(II) ions in Fehling’s solution to form a red precipitate of copper(I) oxide, making formic acid the correct answer.

Option C: CH₃COCH₃ (Acetone): Acetone is a ketone, and ketones do not typically react with Fehling’s solution.

Option D: CH₂Cl - CH₂Cl (Ethylene dichloride): Ethylene dichloride is an alkyl halide, and alkyl halides do not react with Fehling’s solution.

Therefore, the correct answer is Option B: HCOOH (Formic acid), which reacts with Fehling’s solution.

When Fe³⁺ (iron(III)) ions react with potassium thiocyanate (KCNS), they form a blood-red complex, which is commonly known as the iron(III)-thiocyanate complex. The reaction is:

This gives the characteristic blood red color.

• Cu²⁺ (Copper(II)) forms a blue complex with KCNS, not red.
• Al³⁺ (Aluminum(III)) does not form a red complex with KCNS.
• Zn²⁺ (Zinc(II)) does not form a red complex with KCNS.

Thus, the correct answer is Option B: Fe³⁺.

Vapour pressure is a surface phenomenon, when the surface area is more, vapour pressure will be more. When we add solute, what we do is we decrease the vapour pressure of solvent because same of the salt ions will be present at the solvent surface, thus taking place of same of the solvent particles which were actively participating in maintain, that previous high value of vapour pressure. So, the equilibrium vapour pressure value decreases. Thus, dissolving salt in water results in decreasing of equilibrium vapour pressure.

• The internal energy of a substance is the total energy contained within its system.
• It includes:
  • Rotational energy: Energy due to the rotation of molecules.
  • Vibrational energy: Energy due to the vibration of atoms within molecules.
  • Translational energy: Energy due to the movement of molecules in space.
  • Energy due to gravitational pull: Typically negligible at the molecular level and does not contribute to the internal energy of a substance.

Thus, the internal energy does not depend on gravitational energy.

A reaction in an electrochemical cell is spontaneous if the cell potential is positive. The cell potential is a measure of the electrical potential difference between the two half-cells in the electrochemical reaction.

• If the cell potential is positive, the reaction is spontaneous and can occur without external energy.
• If the cell potential is negative, the reaction is non-spontaneous, meaning it cannot occur without external energy input.
• If the cell potential is zero, the reaction is at equilibrium, and there is no net movement of electrons.

Thus, the correct answer is Option A: Positive.

2- Acetoxybenzoic acid is the chemical name of aspirin. Aspirin is a commonly used antipyretic medicine i.e. medicine to lower the fever.

An exothermic reaction is a chemical reaction that releases energy, typically in the form of heat, and has a negative ΔH (enthalpy change).

Option A: The reaction H₂ (g) + Cl₂ (g) → 2HCl (g) has a negative ΔH value of −184.6 kJ, indicating that it is an exothermic reaction. Energy is released as the reaction proceeds.

Option B: The reaction N₂ (g) + O₂ (g) → 2NO (g) has a positive ΔH value of +180.8 kJ, indicating that it is an endothermic reaction (energy is absorbed).

Option C: The reaction C (graphite) + H₂O (g) → CO (g) + H₂ (g) has a negative ΔH value of −131.4 kJ, indicating that it is also exothermic. However, the value is smaller than the one in Option A.

Option D: The reaction C (graphite) + 2S (s) → CS₂ (l) requires 91.9 kJ (positive ΔH), indicating that it is an endothermic reaction.

Thus, the correct answer is Option A because it represents an exothermic reaction.

In the process of silver plating of copper, K[Ag(CN)₂] (potassium silver cyanide) is used instead of AgNO₃ (silver nitrate) to avoid the displacement of silver by copper.

• The cyanide complex [Ag(CN)₂]⁻ prevents the free availability of Ag⁺ ions in the solution, thus avoiding the displacement reaction where copper might displace silver from a simple silver salt like AgNO₃.
• Copper cannot displace silver from the [Ag(CN)₂]⁻ complex, so it ensures a more controlled deposition of silver onto copper without interference.

Other options:

• Option A: The thin layer of Ag is indeed formed, but this is a consequence, not the reason.
• Option B: More voltage is not required for this reason.
• Option C: While Ag⁺ ions are present in the complex, the key factor is preventing displacement, not their complete removal.

Thus, the correct answer is Option D.

The dye test is given by aromatic primary amines, such as aniline. This reaction involves the formation of azo compounds when the amine reacts with nitrous acid and a diazotizable substrate, followed by coupling to form a coloured compound.

Aniline, being an aromatic 1° amine, undergoes this reaction effectively.

When a quantity of electricity passes is one faraday, then the mass deposited at the electrode is equal to E ions being discharged i.e., one gram equivalent weight.

The electrode potentials (E°) of elements A, B, C, and D are given as -1.36 V, -0.32 V, 0 V, and -1.26 V, respectively. To determine the decreasing reactivity order, we need to consider their tendencies to act as reducing agents.

A more negative electrode potential indicates a stronger reducing agent because the element is more likely to be oxidized. Therefore, we arrange the elements from the most negative to the least negative electrode potential:

• A: -1.36 V (most negative)

• D: -1.26 V

• B: -0.32 V

• C: 0 V (least reactive)

Thus, the decreasing reactivity order of these elements is {A > D > B > C}

2g of H₂ ​ at S.T.P. occupy 22400 cm³
∴10⁻² g of H₂ ​at S.T.P. occupy

When the densities of the ore particles and gangue particles are different, the ore can be concentrated using the gravity separation method. This method takes advantage of the difference in densities between the ore and the gangue. The denser ore particles will settle at the bottom, while the less dense gangue particles will float or can be removed by washing.

• Hand-picking is used when the ore and gangue are sufficiently different in appearance.
• Electromagnetic separation is used for ores containing magnetic minerals.
• Froth-flotation process is used for ores containing hydrophobic particles, usually for sulfide ores.

Therefore, the correct method for concentrating ores based on density differences is gravity separation method.

Thus, the correct answer is Option D: gravity separation method.

A pseudo solid refers to a substance that behaves like a solid but does not have a well-defined crystalline structure. It lacks a regular repeating pattern of atoms, unlike true solids.

Glass is considered a pseudo solid because, despite appearing solid, it has an amorphous structure, meaning its atoms are not arranged in a regular, repeating pattern like in crystalline solids. Glass has some characteristics of a liquid over long periods, such as very slow movement of atoms, though it appears solid at room temperature.

Other options:

• Diamond (Option A) is a true crystalline solid.
• Rock salt (Option C) is a crystalline solid.
• CaCO₃ (Option D) is also a crystalline solid.

Thus, the correct answer is Option B: Glass.

The hybridization between P and Cl in PCl₅ is sp³d. This is because P in its ground state has the valence electrons occupancy as two in s orbital, three in p orbitals since it has five valence electrons.