SRMJEEE Chemistry Mock Test - 5 - JEE MCQ

To determine the number of isomeric acyclic alcohols and ethers for the molecular formula C₄H₈O:

• Acyclic alcohols: These are compounds containing hydroxyl (-OH) groups attached to open-chain carbon structures.
• Possible structures:
  • Butan-1-ol
  • Butan-2-ol
  • Isobutanol (2-methylpropan-1-ol)
  • Butan-3-ol

In total, there are four possible acyclic alcohols.

• Ethers: These compounds have an oxygen atom connected to two alkyl or aryl groups.
• Possible structures:
  • Dimethyl ether
  • Methyl ethyl ether
  • Diethyl ether
  • Butyl methyl ether

In total, there are four possible acyclic ethers.

Conclusion: The total number of isomeric acyclic alcohols and ethers for C₄H₈O is eight.

The organic compound that shows a positive Fehling test and Iodoform test is:

• Ethanal

Here’s why:

• Fehling test: This test is used to identify reducing sugars or aldehydes. Ethanal, being an aldehyde, gives a positive result.
• Iodoform test: This test identifies methyl ketones or ethanol. Ethanal can be oxidised to acetic acid, which can then yield a positive result.

Other options do not meet both criteria:

• Methanal: Positive for Fehling but not for Iodoform.
• Ethanol: Positive for Iodoform but not for Fehling.
• Propanone: Positive for Iodoform but not for Fehling.

When calcium carbide (CaC₂) reacts with water (H₂O), the following occurs:

• The reaction produces acetylene, a colourless gas.
• Acetylene is known for its use in welding and as a fuel.
• This reaction highlights the reactivity of calcium carbide with moisture.

DNA is deoxyribonucleic acid. It contains deoxy ribose sugar, a base and a phosphate group.DNA has deoxyribose, a base and the third component is phosphoric acid.

When sodium borate reacts with concentrated sulphuric acid and ethanol, it produces a compound known as 'A'. This compound is notable for burning with a green-edged flame.

• The compound 'A' is typically a type of borate derived from the reaction.
• Key characteristics of the compound include:
• Presence of boron and oxygen in its structure.
• Formation of a green flame during combustion, indicating the presence of certain elements.
• Common compounds that may result from this reaction are:
• H₂B₄O₇ - Boric acid derivative.
• H₃BO₃ - Another boric acid form.
• (C₂H₅)₂B₄O₇ - A borate ester.
• (C₂H₅)₃BO₃ - Another possible product.

Calcium (Ca) has atomic number 20 and mass number 40. Which of the following statements is not correct about Ca atom?

To analyse the properties of a calcium atom:

• Protons: Calcium has 20 protons, indicated by its atomic number.
• Neutrons: To find the number of neutrons, subtract the atomic number from the mass number: 40 - 20 = 20 neutrons.
• Electrons: In a neutral atom, the number of electrons equals the number of protons, so there are also 20 electrons.

Now, evaluating the statements:

• A: The number of protons is the same as the number of neutrons. (Incorrect, as they are both 20 but the statement implies equivalence incorrectly)
• B: The number of electrons is the same as the number of neutrons. (Incorrect, as there are 20 electrons and 20 neutrons)
• C: The number of protons is half of the number of neutrons. (Incorrect, as both are equal)
• D: The number of nucleons is double the number of neutrons. (Correct, as nucleons include both protons and neutrons)

Thus, the statement that is not correct is A, B, and C, with a focus on A being particularly misleading.

The electrophile in the chlorination of benzene, when using FeCl₃, is

• Cl⁺

During the process:

• FeCl₃ acts as a catalyst, facilitating the generation of the electrophile.
• The chlorine molecule (Cl₂) interacts with FeCl₃, resulting in the formation of Cl⁺.
• This positively charged chlorine ion (Cl⁺) is the active species that reacts with benzene.

Other species, such as Cl⁻ and FeCl₃ itself, do not serve as the electrophile in this reaction.

The compound with the longest carbon-carbon double bond length is influenced by several factors:

• The presence of substituents around the double bond can affect its length.
• In general, double bonds with fewer substituents tend to be longer.
• Conjugation or resonance can also play a role in bond length.
• Among the options provided, the compound with the least steric hindrance and no additional conjugation will have the longest double bond.

Therefore, by analysing the structures of each compound, it can be concluded that the compound with the maximum carbon-carbon double bond length is the one with the least substituents and steric interaction.

To determine whether a compound is aromatic, it must meet specific criteria:

• The compound must be cyclic and planar.
• It must have a continuous ring of p-orbitals.
• The compound must follow Hückel's rule, which states it should have (4n + 2) π electrons, where n is a non-negative integer.

To evaluate the options:

• Examine the structure of each compound for cyclicity and planarity.
• Count the number of π electrons available in the ring system.
• Verify if the compound adheres to Hückel's rule.

By applying these criteria, you can identify which compound is aromatic.

The paramagnetism of the O₂ molecule arises from the presence of two electrons with parallel spins in:

• Anti-Bonding π-orbitals

This configuration is responsible for the molecule's magnetic properties due to the unpaired electrons that create a magnetic moment.

The reaction of carbon monoxide with caustic soda (NaOH) yields a specific salt.

This reaction typically produces:

• Sodium formate (HCOONa).

Key points to note:

• Carbon monoxide reacts with NaOH in a specific reaction.
• The product is a salt known as sodium formate.

To find the heat released when mixing HNO₃ and NaOH, follow these steps:

• Heat of neutralisation: The heat released during the reaction of a strong acid and a strong base is -57.0 kJ per mole.
• Moles of reactants: You have 0.5 moles of HNO₃ and 0.2 moles of NaOH. The reaction will be limited by the smaller amount of base.
• Limiting reactant: Since NaOH is present in lesser quantity (0.2 moles), it will determine the amount of heat released.
• Heat calculation: The heat released is calculated by:

Heat released = Moles of NaOH × Heat of neutralisation

• Heat released = 0.2 moles × -57.0 kJ/mole
• Heat released = -11.40 kJ

The amount of heat released is therefore 11.40 kJ.

Conditions for the Formation of Atomic Hydrogen

The conversion of molecular hydrogen (H₂) into atomic hydrogen (H) is influenced by temperature and pressure. The following conditions are most favourable:

• High temperature: This increases the energy of the molecules, promoting the breaking of the H-H bonds in molecular hydrogen.
• Low pressure: A decrease in pressure favours the formation of gaseous products, as atomic hydrogen occupies more volume than molecular hydrogen.

In summary, the ideal conditions for producing atomic hydrogen are high temperature combined with low pressure.

The role of a catalyst in a chemical reaction is to alter:

• Activation energy: It lowers the energy barrier needed for the reaction, allowing it to proceed more easily.
• Final product: The catalyst does not change the nature of the final product.
• Heat of reaction: This remains unchanged as the catalyst does not affect the overall energy change.
• Equilibrium constant: The catalyst does not impact the position of equilibrium.

Aspirin is a type of medication that serves various purposes.

• Antipyretic: It helps reduce fever.
• Anti-inflammatory: It alleviates inflammation and pain.
• Analgesic: It provides relief from mild to moderate pain.

It's important to note that aspirin is not an antibiotic or antiseptic. Always consult a healthcare professional before use.

For the Gibbs free energy change (∆G):

• It is not always less than or greater than enthalpy change (∆H).

• ∆G can be less than, greater than, or equal to ∆H depending on the system and conditions.

• Its relationship with ∆H is influenced by temperature and entropy changes.

Stability Order of Butenes

The stability of the three compounds can be assessed based on the degree of substitution and steric hindrance:

• 1-butene: This compound has the least stability due to fewer substituents on the double bond.
• cis-2-butene: This is more stable than 1-butene but less stable than trans-2-butene because the cis configuration introduces steric strain between the methyl groups.
• trans-2-butene: This is the most stable isomer as it has the greatest substituent separation, reducing steric hindrance.

Thus, the order of stability is:

• 1-butene (least stable)
• cis-2-butene
• trans-2-butene (most stable)

The ionisation potential keep on decreasing regularly as we move down a group from one element to the other. Because on moving down the group the atomic size increases gradually due to the addition of one new principal energy shell at each succeeding element. As a result, the force of attraction by the nucleus for the valence electrons decreases and the shielding effect increases. Consequently, ionisation potential also decreases.

To determine the temperature at which the average speed of CH₄ molecules matches that of O₂ at 300 K, consider the following:

• Average speed of gas molecules is affected by their mass and temperature.
• The formula for average speed is directly related to the temperature and inversely related to the square root of molecular mass.
• CH₄ (methane) is lighter than O₂ (oxygen), meaning it will have a higher average speed at a given temperature.
• To find the temperature for CH₄ where its speed equals that of O₂ at 300 K, we use the relationship:
• Temperature of CH₄ must be higher due to its lower mass.
• By calculations, the temperature required for CH₄ is approximately 1200 K.

To determine the equivalent conductance of C₂H₅COOH, we can use the following relationships:

• Conductance is the measure of a solution's ability to conduct electricity.
• The equivalent conductance at infinite dilution can be represented as follows:
• Λ₀(NaCl) = 126.45 ohm⁻¹ cm²
• Λ₀(HCl) = 426.16 ohm⁻¹ cm²
• Λ₀(C₂H₅COONa) = 91 ohm⁻¹ cm²

Applying the concept of ionic dissociation, we find:

• For C₂H₅COOH, we note that it is a weak acid and partially dissociates.
• This dissociation can be related to the conductance of its salt form, C₂H₅COONa.
• The equivalent conductance of C₂H₅COOH can be approximated by considering its contribution from ions.

Using the given values, we can calculate:

• Λ₀(C₂H₅COOH) = Λ₀(C₂H₅COONa) + Λ₀(H⁺) - Λ₀(OH⁻)
• Substituting the values, we get:
• Λ₀(C₂H₅COOH) = 91 + 426.16 - 0 (since OH⁻ is not present in the weak acid context)
• This results in an approximate equivalent conductance of:
• Λ₀(C₂H₅COOH) ≈ 517.16 ohm⁻¹ cm²

This value, rounded to a suitable precision, provides the equivalent conductance of C₂H₅COOH. However, further verification with experimental data may be necessary for accuracy.

To determine which compound is the most soluble in water, consider the following points:

• Manganese sulfide (MnS): Generally low solubility in water.
• Zinc sulfide (ZnS): Known for its low solubility; dissolves poorly in water.
• Bismuth trisulfide (Bi₂S₃): Also has very limited solubility.
• Silver sulfide (Ag₂S): Practically insoluble in water.

Among these compounds, ZnS displays the highest solubility due to its unique properties compared to the others listed, although it is still considered only sparingly soluble.

The Fischer-Tropsch process is primarily used to produce:

• Synthetic petrol - a liquid fuel that can be used in internal combustion engines, derived from coal or natural gas.

This process converts carbon monoxide and hydrogen into liquid hydrocarbons through a series of chemical reactions. It is a crucial method for producing alternative fuels, especially in regions with abundant natural gas or coal resources.

To identify functional isomers, we need to consider compounds that have the same molecular formula but different functional groups.

• Option A:

  Both compounds are alcohols but differ in structure: one is a primary alcohol and the other is a secondary alcohol, making them functional isomers.

• Option B:

  Both compounds are alcohols; however, they have different chain lengths and structures but share the same functional group, so they are not functional isomers.

• Option C:

  One is an alcohol while the other is an alkyl chloride. They have different functional groups, thus they are functional isomers.

• Option D:

  One is an alcohol while the other is an ether. They exhibit different functional groups, making them functional isomers as well.

Conclusion: The pairs in Options A, C, and D are functional isomers due to their differing functional groups, while Option B is not.

The half-life of a radioactive element is 100 years.

During the half-life period, the following occurs:

• The mass of the radioactive element decreases by 50%.
• This means that in 100 years, half of its original mass will have disintegrated.

Thus, the time required for the element to disintegrate 50% of its mass is 100 years.

The chemicals involved in the production of methyl isocyanate, which led to the Bhopal Tragedy, include:

• Methyl amine - A key ingredient in the synthesis.
• Phosgene - Another critical chemical in the manufacturing process.

Phosphine and dimethyl amine are not directly associated with the production of methyl isocyanate in this context.

The compound that can form intramolecular hydrogen bonds is:

• Intramolecular hydrogen bonds occur when a hydrogen atom covalently bonded to an electronegative atom forms a bond with another electronegative atom within the same molecule.
• m-Hydroxybenzaldehyde does not have the necessary structure to facilitate this bonding.
• Benzaldehyde lacks hydroxyl groups for intramolecular interactions.
• Salicylaldehyde features both a hydroxyl and an aldehyde group, allowing it to form intramolecular hydrogen bonds effectively.
• p-Hydroxybenzaldehyde also does not support intramolecular hydrogen bonding due to its orientation.

The low reactivity of vinyl chloride and chlorobenzene can be attributed to:

• The presence of a negative mesomeric effect, which stabilises the molecule and reduces its reactivity.
• Chlorine's greater electronegativity compared to carbon, leading to a polar bond that further lowers reactivity.

These factors result in both compounds being less reactive in chemical reactions.

To determine the molecular formula of the dibasic acid:

• Composition: The acid contains 26.7% carbon (C) and 2.2% hydrogen (H).
• Calculate Oxygen: The remainder is oxygen (O). Therefore, the percentage of oxygen is:
  • 100% - (26.7% + 2.2%) = 71.1% O
• Empirical Formula: Convert the percentages to moles:
  • C: 26.7 g / 12.01 g/mol = 2.22 moles
  • H: 2.2 g / 1.008 g/mol = 2.18 moles
  • O: 71.1 g / 16.00 g/mol = 4.43 moles
• Ratios: Divide by the smallest number of moles (approximately 2.18):
  • C: 2.22 / 2.18 ≈ 1.02
  • H: 2.18 / 2.18 = 1
  • O: 4.43 / 2.18 ≈ 2.03
• Thus, the empirical formula is approximately C1H1O2, or C2H2O4 when multiplied to obtain whole numbers.
• Molecular Weight: The vapour density of the diethyl ester is 73, which suggests a molar mass of 146 (since molar mass = 2 x vapour density).
• Final Formula: The molecular formula consistent with the empirical formula is C2H2O4.

Plexiglass (PMMA) is a polymer formed from the polymerisation of

• Methyl methacrylate (MMA), which is the primary monomer used in its production.

• This process involves the transformation of MMA into a long-chain polymer, resulting in the clear, durable material known as Plexiglass.

• Plexiglass is widely used for its transparency and resistance to UV light, making it an excellent alternative to glass in various applications.