datavorous/entrance-exam-dataset huggingface dataset:
Why does iodoform have appreciable antiseptic properties?

Options:
A Iodoform releases free iodine atoms when in contact with body fluids, which exhibit antiseptic properties.
B Iodoform can form strong hydrogen bonds with water, leading to effective antimicrobial action.
C Iodoform is a polar compound that disrupts microbial cell membranes.
D Iodoform has a pleasant odor that repels insects and prevents microbial infestations.

The correct answer is:
Iodoform releases free iodine atoms when in contact with body fluids, which exhibit antiseptic properties.

Solution:
Correct Option is : (A)
Iodoform releases free iodine atoms when in contact with body fluids, which exhibit antiseptic properties.

Topic: Chemistry, Haloalkanes and Haloarenes, NEET
Why does leather get hardened after tanning?

Options:
A Tanning increases the flexibility of leather fibers.
B Tanning reduces the intermolecular forces in leather.
C Tanning removes water from the leather, making it rigid.
D Tanning introduces a plasticizing agent to the leather.

The correct answer is:
Tanning removes water from the leather, making it rigid.

Solution:
Correct Option is : (C)
Tanning removes water from the leather, making it rigid.

Topic: Chemistry, Surface Chemistry, NEET
Why does lithium, despite having the most negative Eo value among the alkali metals, react less vigorously with water compared to sodium?

Options:
A Lithium has a larger size and lower hydration energy.
B Lithium has a smaller size and lower hydration energy.
C Sodium has a larger size and higher hydration energy.
D Sodium has a smaller size and higher hydration energy.

The correct answer is:
Lithium has a smaller size and lower hydration energy.

Solution:
The less vigorous reaction of lithium with water, despite having a more negative Eo value, is attributed to its small size and very high hydration energy, which makes it less reactive than sodium.

Topic: Chemistry, s Block Elements, NEET
Why does maltose exhibit reducing properties?

Options:
A Because it contains an aldehyde group
B Because it contains a ketone group
C Because it contains a carboxylic acid group
D Because it contains a hydroxyl group

The correct answer is:
Because it contains an aldehyde group

Solution:
Maltose exhibits reducing properties due to the presence of an aldehyde group.

Topic: Chemistry, Biomolecules, NEET
Why does NH3act as a Lewis base?

Options:
A Due to the lone pair of electrons on nitrogen, it can donate a pair of electrons to form a coordinate covalent bond.
B NH3has a high electron affinity, allowing it to readily accept electrons.
C NH3is a highly polar molecule, making it prone to electron donation.
D NH3has a high ionization energy, enabling it to act as a Lewis base.

The correct answer is:
Due to the lone pair of electrons on nitrogen, it can donate a pair of electrons to form a coordinate covalent bond.

Solution:
Correct Option is : (A)
Due to the lone pair of electrons on nitrogen, it can donate a pair of electrons to form a coordinate covalent bond.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does NH3form a hydrogen bond but PH3does not?

Options:
A PH3has a smaller electronegativity difference with hydrogen.
B NH3has a larger electronegativity difference with hydrogen.
C PH3is a stronger base than NH3.
D PH3forms covalent bonds with hydrogen.

The correct answer is:
NH3has a larger electronegativity difference with hydrogen.

Solution:
Correct Option is : (B)
NH3has a larger electronegativity difference with hydrogen.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does nitric acid act as an oxidizing agent and react with PbO but not with PbO2?

Options:
A Nitric acid prefers to react with lower oxidation state compounds.
B PbO has a higher electron affinity than PbO2.
C PbO2is already in its highest oxidation state, making it unreactive with nitric acid.
D Nitric acid forms a protective layer on the surface of PbO2, preventing further reaction.

The correct answer is:
PbO2is already in its highest oxidation state, making it unreactive with nitric acid.

Solution:
Correct Option is : (C)
PbO2is already in its highest oxidation state, making it unreactive with nitric acid.

Topic: Chemistry, Redox Reactions, NEET
Why does nitrogen have positive electron gain enthalpy whereas oxygen has negative? However, oxygen has lower ionisation enthalpy than nitrogen. Explain.

Options:
A Nitrogen's stable half-filled p-orbital (2p³) resists the addition of extra electrons, resulting in positive electron gain enthalpy.
B Oxygen, with a 2p³ configuration, achieves stability by removing one electron, leading to a negative electron gain enthalpy.
C Nitrogen's higher ionisation enthalpy makes it less favourable to lose electrons compared to oxygen.
D Oxygen's smaller atomic size allows for easier removal of electrons, resulting in a negative electron gain enthalpy.

The correct answer is:
Nitrogen's stable half-filled p-orbital (2p³) resists the addition of extra electrons, resulting in positive electron gain enthalpy.

Solution:
Correct Option is : (A)
Nitrogen's stable half-filled p-orbital (2p³) resists the addition of extra electrons, resulting in positive electron gain enthalpy.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
Why does nitrogen not form pentahalides?

Options:
A Non-availability of d orbitals
B Lack of reactivity with halogens
C Low atomic size
D High ionization energy

The correct answer is:
Non-availability of d orbitals

Solution:
Nitrogen does not form pentahalides due to the non-availability of d orbitals in its valence shell.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why does nitrogen show catenation properties less than phosphorus?

Options:
A Nitrogen has a smaller atomic size than phosphorus.
B Nitrogen forms weaker covalent bonds.
C Nitrogen has a higher electronegativity.
D Nitrogen has a higher atomic number.

The correct answer is:
Nitrogen has a smaller atomic size than phosphorus.

Solution:
Correct Option is : (A)
Nitrogen has a smaller atomic size than phosphorus.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does NO2dimerize?

Options:
A Due to the presence of unpaired electrons in the nitrogen atom, NO2molecules are attracted to each other.
B NO2has a bent shape, allowing for efficient dimerization.
C NO2molecules have a high electron affinity, promoting dimerization.
D NO2undergoes a redox reaction, leading to dimerization

The correct answer is:
Due to the presence of unpaired electrons in the nitrogen atom, NO2molecules are attracted to each other.

Solution:
Correct Option is : (A)
Due to the presence of unpaired electrons in the nitrogen atom, NO2molecules are attracted to each other.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does O3act as a powerful oxidizing agent?

Options:
A Due to the presence of a lone pair of electrons.
B Due to the presence of a double bond.
C Due to the higher oxidation state of oxygen.
D Due to the presence of an unstable O-O bond.

The correct answer is:
Due to the presence of an unstable O-O bond.

Solution:
Correct Option is : (D)
Due to the presence of an unstable O-O bond.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does oxygen have a smaller first ionization enthalpy compared to nitrogen?

Options:
A Oxygen has more electrons.
B Oxygen has a smaller nucleus.
C Oxygen has less shielding.
D Oxygen has greater electron-electron repulsion.

The correct answer is:
Oxygen has greater electron-electron repulsion.

Solution:
In the oxygen atom, two of the four 2p-electrons must occupy the same 2p-orbital, resulting in increased electron-electron repulsion, making it easier to remove an electron compared to nitrogen.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, NEET
Why does PCl3fume in moisture?

Options:
A PCl3reacts with moisture to form hydrochloric acid, which produces fumes.
B PCl3has a low boiling point, causing it to vaporize and produce fumes in the presence of moisture.
C PCl3undergoes a redox reaction with water, leading to the release of gaseous chlorine.
D PCl3is highly volatile and readily produces vapors when exposed to moisture.

The correct answer is:
PCl3reacts with moisture to form hydrochloric acid, which produces fumes.

Solution:
Correct Option is : (A)
PCl3reacts with moisture to form hydrochloric acid, which produces fumes.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does PH3have a lower boiling point than NH3?

Options:
A PH3molecules have stronger hydrogen bonding.
B PH3molecules are not associated through hydrogen bonding.
C PH3has a lower molecular weight.
D PH3is more polar than NH3.

The correct answer is:
PH3molecules are not associated through hydrogen bonding.

Solution:
Correct Option is : (B)
PH3molecules are not associated through hydrogen bonding.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does physical adsorption occur readily at low temperatures, according to Le-Chatelier’s principle?

Options:
A It is an endothermic process.
B It is an exothermic process.
C It is independent of temperature.
D Temperature has no effect on adsorption.

The correct answer is:
It is an exothermic process.

Solution:
The paragraph states that since the adsorption process is exothermic, physical adsorption occurs readily at low temperatures.

Topic: Chemistry, Surface Chemistry, NEET
Why does physisorption decrease with the increase of temperature?

Options:
A Increased temperature leads to a decrease in the kinetic energy of gas molecules, reducing their ability to adhere to the surface.
B Increased temperature enhances the kinetic energy of gas molecules, making them less likely to be trapped on the surface.
C Physisorption is not affected by temperature.
D Increased temperature increases the strength of van der Waals forces, making physisorption more difficult.

The correct answer is:
Increased temperature enhances the kinetic energy of gas molecules, making them less likely to be trapped on the surface.

Solution:
Correct Option is : (B)
Increased temperature enhances the kinetic energy of gas molecules, making them less likely to be trapped on the surface.

Topic: Chemistry, Surface Chemistry, NEET
Why does presence of a nitro group make the benzene ring less reactive in comparison to the unsubstituted benzene ring. Explain.

Options:
A The nitro group is a strong electron-donating group that enhances the reactivity of the benzene ring.
B The nitro group is a powerful electron-withdrawing group that reduces the electron density on the benzene ring.
C The nitro group has no significant effect on the reactivity of the benzene ring.
D The nitro group acts as a resonance donor, increasing the electron density on the benzene ring.

The correct answer is:
The nitro group is a powerful electron-withdrawing group that reduces the electron density on the benzene ring.

Solution:
Correct Option is : (B)
The nitro group is a powerful electron-withdrawing group that reduces the electron density on the benzene ring.

Topic: Chemistry, Hydrocarbons, NEET
Why does R3P = O exist but R3N = O does not (R = alkyl group)?

Options:
A Nitrogen's higher electronegativity stabilizes positive charge on nitrogen.
B Phosphorus's lower electronegativity stabilizes positive charge on phosphorus.
C Nitrogen's hybridization state is not conducive to positive charge accommodation.
D Phosphorus's sp3hybridization allows for positive charge stabilization.

The correct answer is:
Phosphorus's lower electronegativity stabilizes positive charge on phosphorus.

Solution:
Correct Option is : (B)
Phosphorus's lower electronegativity stabilizes positive charge on phosphorus.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does SO3act as an electrophile?

Options:
A Because it has a high electron density due to the presence of lone pairs on sulphur.
B Because it has a negative charge on sulphur, making it electron-deficient.
C Three highly electronegative oxygen atoms are attached to sulphur atom. It makes sulphur atom electron deficient. Due to resonance also, sulphur acquires positive charge. Both these factors make SO3an electrophile.
D Because it has a highly non-polar covalent bond between sulphur and oxygen.

The correct answer is:
Three highly electronegative oxygen atoms are attached to sulphur atom. It makes sulphur atom electron deficient. Due to resonance also, sulphur acquires positive charge. Both these factors make SO3an electrophile.

Solution:
Correct Option is : (C)
Three highly electronegative oxygen atoms are attached to sulphur atom. It makes sulphur atom electron deficient. Due to resonance also, sulphur acquires positive charge. Both these factors make SO3an electrophile.

Topic: Chemistry, General Organic Chemistry, NEET
Why does sodium borohydride not reduce the carboxyl group in carboxylic acids?

Options:
A Sodium borohydride is too reactive.
B Carboxylic acids are not reducible.
C Sodium borohydride is not a strong reducing agent.
D Sodium borohydride reacts with the alcohol formed.

The correct answer is:
Sodium borohydride is not a strong reducing agent.

Solution:
Sodium borohydride is not a strong enough reducing agent to reduce the carboxyl group in carboxylic acids efficiently. It is more commonly used for reducing aldehydes and ketones to alcohols.

Topic: Chemistry, Aldehydes, Ketones and Carboxylic Acids, NEET
Why does some external heating often need to be applied to initiate the reaction between dioxygen (O2) and other elements?

Options:
A To lower the bond dissociation enthalpy of the O-O double bond
B To increase the bond dissociation enthalpy of the O-O double bond
C To decrease the reactivity of dioxygen
D To increase the number of electrons in dioxygen

The correct answer is:
To lower the bond dissociation enthalpy of the O-O double bond

Solution:
The paragraph explains that to initiate the reaction between dioxygen and other elements, some external heating is required, as the bond dissociation enthalpy of the oxygen-oxygen (O-O) double bond is high (493.4 kJ mol⁻¹). Heating lowers this bond dissociation enthalpy.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why does table salt, NaCl, some times appear yellow in colour?

Options:
A Because it naturally has a yellow tint.
B Because it absorbs blue light and reflects yellow light.
C Because it is highly reactive with air, causing oxidation and a yellow hue.
D Yellow colour in sodium chloride is due to metal excess defect due to which unpaired electrons occupy anionic sites. These sites are called F-centres.

The correct answer is:
Yellow colour in sodium chloride is due to metal excess defect due to which unpaired electrons occupy anionic sites. These sites are called F-centres.

Solution:
Correct Option is : (D)
Yellow colour in sodium chloride is due to metal excess defect due to which unpaired electrons occupy anionic sites. These sites are called F-centres.

Topic: Chemistry, Solid State, NEET
Why does the addition of an inert gas at constant volume not disturb the equilibrium?

Options:
A Because inert gases do not affect equilibrium.
B Because inert gases react with the substances involved in the reaction.
C Because inert gases change the partial pressures and concentrations of the reactants.
D Because inert gases change the temperature of the reaction.

The correct answer is:
Because inert gases do not affect equilibrium.

Solution:
The addition of an inert gas at constant volume does not disturb the equilibrium because inert gases do not affect the equilibrium conditions.

Topic: Chemistry, Chemical Equilibrium, NEET
Why does the air become dry in the presence of silica gel?

Options:
A Silica gel absorbs water molecules
B Silica gel releases water molecules
C Silica gel disperses water molecules
D Silica gel repels water molecules

The correct answer is:
Silica gel absorbs water molecules

Solution:
The paragraph mentions that the air becomes dry in the presence of silica gel because the water molecules get adsorbed on the surface of the gel.

Topic: Chemistry, Surface Chemistry, NEET
Why does the carbon atom in carbocations become an electrophilic center?

Options:
A It has a positive charge.
B It has a sextet configuration.
C It has a partial positive charge.
D It has an unpaired electron.

The correct answer is:
It has a partial positive charge.

Solution:
In carbocations, due to the polarity of the C-X bond, a partial positive charge is generated on the carbon atom, making it an electrophilic center.

Topic: Chemistry, General Organic Chemistry, NEET
Why does the complex [Ti(H2O)6]3+exhibit a violet colour based on crystal field theory?

Options:
A The violet colour arises because of d-d transition due to d1configuration of Titanium
B The violet colour is due to the weak ligand-field interactions between water molecules and the titanium ion.
C The violet colour results from the high spin state of the complex, causing the absorption of violet light.
D The violet colour is a result of the low spin state of the complex, causing the absorption of violet light.

The correct answer is:
The violet colour arises because of d-d transition due to d1configuration of Titanium

Solution:
Correct Option is : (A)
The violet colour arises because of d-d transition due to d1configuration of Titanium

Topic: Chemistry, Coordination Compounds, NEET
Why does the compound AgF₂ act as a very strong oxidizing agent if formed?

Options:
A It contains a high concentration of silver ions.
B It contains a high concentration of fluorine atoms.
C It is an unstable compound, leading to increased reactivity.
D It has a high affinity for electrons.

The correct answer is:
It is an unstable compound, leading to increased reactivity.

Solution:
Correct Option is : (C)
It is an unstable compound, leading to increased reactivity.

Topic: Chemistry, Redox Reactions, NEET
Why does the conductivity of a solution decrease with dilution?

Options:
A Dilution increases the number of ions
B Dilution decreases the number of ions
C Dilution has no effect on conductivity
D Dilution increases the resistance of the solution

The correct answer is:
Dilution decreases the number of ions

Solution:
Correct Option is : (B)
Dilution decreases the number of ions

Topic: Chemistry, Electrochemistry, NEET
Why does the conductivity of very pure water increase when electrolytes are dissolved in it?

Options:
A Due to an increase in the number of valence electrons
B Due to the presence of ions furnished by the electrolytes
C Due to a decrease in temperature
D Due to an increase in pressure

The correct answer is:
Due to the presence of ions furnished by the electrolytes

Solution:
The conductivity of very pure water increases when electrolytes are dissolved in it because they furnish their own ions in the solution.

Topic: Chemistry, Electrochemistry, NEET
Why does the decrease in ionization enthalpy occur from boron to aluminum?

Options:
A Due to a decrease in size
B Due to an increase in nuclear charge
C Due to the presence of d-electrons
D Due to high screening effect

The correct answer is:
Due to an increase in nuclear charge

Solution:
The decrease in ionization enthalpy from boron to aluminum is associated with an increase in nuclear charge.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does the direct attachment of a phenyl or vinyl group to a carboxylic acid increase its acidity?

Options:
A Due to the presence of resonance structures
B Due to the greater electronegativity of the attached carbon
C Due to the electron-donating effect of the attached group
D Due to the increase in steric hindrance

The correct answer is:
Due to the greater electronegativity of the attached carbon

Solution:
The paragraph explains that the increase in acidity of carboxylic acids when attached to phenyl or vinyl groups is due to the greater electronegativity of the attached carbon.

Topic: Chemistry, Aldehydes, Ketones and Carboxylic Acids, NEET
Why does the electric field of an electromagnetic (EM) wave not contribute to the radiation pressure, even though it exerts a force on a charged particle?

Options:
A The electric field of an EM wave is shielded by vacuum fluctuations.
B The electric field force is cancelled out by the magnetic field force.
C The direction of the force caused by the electric field changes with each half cycle, averaging to zero over a complete cycle.
D The electric field of an EM wave is too weak to contribute to radiation pressure.

The correct answer is:
The direction of the force caused by the electric field changes with each half cycle, averaging to zero over a complete cycle.

Solution:
Correct Option is : (C)
The direction of the force caused by the electric field changes with each half cycle, averaging to zero over a complete cycle.

Topic: Chemistry, Electromagnetic Waves, NEET
Why does the electrical conductivity of semiconductors increase with rise in temperature?

Options:
A Because higher temperatures introduce impurities into the semiconductor.
B Because semiconductors naturally become more conductive as they heat up.
C Because elevated temperatures cause the semiconductor crystal to become more ordered.
D Because electrons from the valence band can jump to the conduction band on increasing temperature.

The correct answer is:
Because electrons from the valence band can jump to the conduction band on increasing temperature.

Solution:
Correct Option is : (D)
Because electrons from the valence band can jump to the conduction band on increasing temperature.

Topic: Chemistry, Solid State, NEET
Why does the energy of the electron in a hydrogen atom have a negative sign for all possible orbits in Bohr's model?

Options:
A Because electrons are negatively charged particles.
B Because the nucleus is positively charged.
C Because the energy of the electron is always lower than that of a free electron at rest.
D Because the energy of the electron is always higher than that of a free electron at rest.

The correct answer is:
Because the energy of the electron is always lower than that of a free electron at rest.

Solution:
The negative sign of the energy indicates that the energy of the electron in the atom is lower than the energy of a free electron at rest.

Topic: Chemistry, Structure of Atom, NEET
Why does the following reaction occur? XeO64-(aq) + 2F-(aq) + 6H+(aq) → XeO3(g) + F2(g) + 3H2O(l) What conclusion can be drawn about the compound Na4XeO6(of which XeO64-is a part) from the reaction?

Options:
A Na4XeO6is highly stable in aqueous solutions.
B XeO64-is a strong reducing agent.
C XeO64-can undergo redox reactions.
D Na4XeO6is unreactive in the presence of acids.

The correct answer is:
XeO64-can undergo redox reactions.

Solution:
Correct Option is : (C)
XeO64-can undergo redox reactions.

Topic: Chemistry, Redox Reactions, NEET
Why does the ionization enthalpy of Cr show unusually high values?

Options:
A It has more s electrons
B It has more p electrons
C It has a d5 configuration
D It has a d10 configuration

The correct answer is:
It has a d5 configuration

Solution:
The paragraph explains that the ionization enthalpy of Cr shows unusually high values because it has a d5 configuration.

Topic: Chemistry, d and f Block Elements, NEET
Why does the ionization enthalpy of Fe2+ lower than that of Mn2+?

Options:
A Fe2+ has d6 configuration
B Fe2+ has fewer s electrons
C Fe2+ has a higher atomic number
D Mn2+ has a d5 configuration

The correct answer is:
Fe2+ has d6 configuration

Solution:
Fe2+ has d6 configuration and Mn2+ has 3d5 configuration. Hence, ionisation enthalpy of Fe2+ is lower than the Mn2+ .

Topic: Chemistry, d and f Block Elements, NEET
Why does the -OH group attached to the benzene ring activate it towards electrophilic substitution?

Options:
A It donates electrons through resonance.
B It withdraws electrons through resonance.
C It donates electrons through inductive effects.
D It withdraws electrons through inductive effect.

The correct answer is:
It donates electrons through resonance.

Solution:
The -OH group in phenols activates the benzene ring through resonance, making it more electron-rich.

Topic: Chemistry, Alcohols Phenols and Ethers, NEET