datavorous/entrance-exam-dataset huggingface dataset:
Why does the presence of electron-withdrawing groups in substituted phenols enhance their acidic strength?

Options:
A They increase electron density in the phenoxide ion.
B They stabilise the phenoxide ion through resonance.
C They decrease the electron density in the phenoxide ion.
D They promote the formation of alkyl groups.

The correct answer is:
They stabilise the phenoxide ion through resonance.

Solution:
Electron-withdrawing groups, such as nitro groups, enhance the acidic strength of phenols by stabilising the resulting phenoxide ion through resonance, making it more likely to donate a proton.

Topic: Chemistry, Alcohols Phenols and Ethers, NEET
Why does the rate of a reaction increase with rise in temperature?

Options:
A Higher temperatures increase the concentration of reactants.
B At higher temperatures, larger fraction of colliding particles can cross the energy barrier (i.e. the activation energy), which leads to faster rate.
C Higher temperatures decrease the number of collisions between molecules.
D Higher temperatures decrease the kinetic energy of reactant molecules.

The correct answer is:
At higher temperatures, larger fraction of colliding particles can cross the energy barrier (i.e. the activation energy), which leads to faster rate.

Solution:
Correct Option is : (B)
At higher temperatures, larger fraction of colliding particles can cross the energy barrier (i.e. the activation energy), which leads to faster rate.

Topic: Chemistry, Chemical Kinetics, NEET
Why does the rate of any reaction generally decreases during the course of the reaction?

Options:
A The concentration of reactants increases as the reaction progresses.
B The rate of a reaction depends on the concentration of reactants. As the reaction progresses, reactants start getting converted to products so the concentration of reactants decreases hence the rate decreases.
C The rate of product formation is independent of the reaction progress.
D As the reaction progresses, the concentration of reactants decreases.

The correct answer is:
The rate of a reaction depends on the concentration of reactants. As the reaction progresses, reactants start getting converted to products so the concentration of reactants decreases hence the rate decreases.

Solution:
Correct Option is : (B)
The rate of a reaction depends on the concentration of reactants. As the reaction progresses, reactants start getting converted to products so the concentration of reactants decreases hence the rate decreases.

Topic: Chemistry, Chemical Kinetics, NEET
Why does the rate of the reaction become independent of the concentration of NH3 at high pressure in the decomposition of gaseous ammonia?

Options:
A Because NH3 becomes a solid at high pressure.
B Because the metal surface gets saturated with gas molecules.
C Because the rate constant (k) changes at high pressure.
D Because the reaction becomes first order at high pressure.

The correct answer is:
Because the metal surface gets saturated with gas molecules.

Solution:
At high pressure, the metal surface becomes saturated with gas molecules, preventing further changes in the concentration of ammonia (NH3) on the catalyst's surface. This saturation makes the rate of the reaction independent of NH3 concentration.

Topic: Chemistry, Chemical Kinetics, NEET
Why does the reaction Cr2O3+ 2Al → Al2O3+ 2Cr, with ∆rG0= –421 kJ, not take place at room temperature even though it is thermodynamically feasible?

Options:
A The activation energy barrier is too high.
B The reaction is kinetically inhibited.
C The reaction is not energetically favorable.
D The equilibrium constant is too low.

The correct answer is:
The activation energy barrier is too high.

Solution:
Correct Option is : (A)
The activation energy barrier is too high.

Topic: Chemistry, General Principles and Processes of Isolation of Metals, NEET
Why does the reactivity of nitrogen differ from phosphorus?

Options:
A Nitrogen forms stronger bonds than phosphorus.
B Nitrogen has a higher ionization energy than phosphorus.
C Nitrogen has a smaller atomic size than phosphorus.
D Nitrogen has a higher electronegativity than phosphorus.

The correct answer is:
Nitrogen has a higher electronegativity than phosphorus.

Solution:
Correct Option is : (D)
Nitrogen has a higher electronegativity than phosphorus.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why does the same reductant, thiosulphate, react differently with iodine and bromine?

Options:
A Iodine is a stronger oxidizing agent than bromine.
B Bromine is a stronger oxidizing agent than iodine.
C The reactivity of thiosulphate depends on the concentration of the reacting species.
D The reactivity of thiosulphate depends on the temperature of the reaction.

The correct answer is:
Bromine is a stronger oxidizing agent than iodine.

Solution:
Correct Option is : (B)
Bromine is a stronger oxidizing agent than iodine.

Topic: Chemistry, Redox Reactions, NEET
Why does the second O – H bond in polyatomic molecules like ethanol and water show a difference in energy compared to the first O – H bond?

Options:
A Due to temperature variations
B Due to bond length differences
C Due to changes in the chemical environment
D Due to differences in the number of bonds

The correct answer is:
Due to changes in the chemical environment

Solution:
The second O – H bond in polyatomic molecules like ethanol and water shows a difference in energy because of changes in the chemical environment.

Topic: Chemistry, Chemical Bonding and Molecular Structure, NEET
Why does the size of the needle of a syringe control flow rate better than the thumb pressure exerted by a doctor while administering an injection?

Options:
A Because thumb pressure directly affects pressure and velocity equally.
B Because the pressure exerted by the doctor depends solely on thumb strength.
C Because the size of the needle affects the velocity squared, giving it a more significant influence on flow rate.
D Because the thumb pressure exerted by a doctor can be precisely measured and controlled.

The correct answer is:
Because the size of the needle affects the velocity squared, giving it a more significant influence on flow rate.

Solution:
Correct Option is : (C)
Because the size of the needle affects the velocity squared, giving it a more significant influence on flow rate.

Topic: Chemistry, Mechanical Properties of Fluids, NEET
Why does the solubility of alkaline earth metal carbonates and sulphates in water decrease down the group?

Options:
A Because the atomic radius of alkaline earth metals increases down the group, leading to weaker ionic bonds and decreased solubility.
B Because the atomic number of alkaline earth metals increases down the group, leading to stronger ionic bonds and decreased solubility.
C Because the electronegativity of alkaline earth metals increases down the group, leading to stronger ionic bonds and decreased solubility.
D Because the number of valence electrons in alkaline earth metals increases down the group, leading to stronger ionic bonds and decreased solubility.

The correct answer is:
Because the atomic radius of alkaline earth metals increases down the group, leading to weaker ionic bonds and decreased solubility.

Solution:
Correct Option is : (A)
Because the atomic radius of alkaline earth metals increases down the group, leading to weaker ionic bonds and decreased solubility.

Topic: Chemistry, s Block Elements, NEET
Why does the solubility of alkaline earth metal hydroxides in water increase down the group?

Options:
A Due to a decrease in atomic size.
B Due to an increase in ionization energy.
C Due to an increase in atomic size and a decrease in ionization energy.
D Due to a decrease in atomic size and an increase in ionization energy.

The correct answer is:
Due to an increase in atomic size and a decrease in ionization energy.

Solution:
Correct Option is : (C)
Due to an increase in atomic size and a decrease in ionization energy.

Topic: Chemistry, s Block Elements, NEET
Why does the solubility of higher carboxylic acids decrease as the number of carbon atoms in the molecule increases?

Options:
A They form covalent bonds with water.
B They have increased hydrophobic interactions.
C They become more polar.
D They have higher vapour pressure.

The correct answer is:
They have increased hydrophobic interactions.

Solution:
The solubility of higher carboxylic acids decreases because they exhibit increased hydrophobic interactions due to the larger hydrocarbon part of their molecules.

Topic: Chemistry, Aldehydes, Ketones and Carboxylic Acids, NEET
Why does the stability of the +5 oxidation state decrease down the group?

Options:
A Increase in size and metallic character
B Presence of d-orbitals
C Inert pair effect
D Change in atomic size

The correct answer is:
Increase in size and metallic character

Solution:
The paragraph explains that the stability of the +5 oxidation state decreases down the group due to an increase in size and metallic character.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why does the stability of the hydrogen halides decrease down the group from fluorine to iodine?

Options:
A Due to a decrease in bond (H–X) dissociation enthalpy
B Due to an increase in bond (H–X) dissociation enthalpy
C Due to a decrease in electron gain enthalpy
D Due to the presence of d orbitals

The correct answer is:
Due to a decrease in bond (H–X) dissociation enthalpy

Solution:
The stability of the hydrogen halides decreases down the group due to a decrease in bond (H–X) dissociation enthalpy.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why does the tendency to exhibit the -3 oxidation state decrease down the group?

Options:
A Increase in metallic character
B Decrease in size
C Presence of d-orbitals
D Inert pair effect

The correct answer is:
Increase in metallic character

Solution:
The paragraph attributes the decrease in the tendency to exhibit the -3 oxidation state to the increase in metallic character down the group.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why does the third ionization enthalpy increase for copper, nickel, and zinc?

Options:
A They have a higher atomic number
B They have a higher number of d electrons
C They have a higher number of p electrons
D They have a higher number of s electrons

The correct answer is:
They have a higher number of d electrons

Solution:
The third ionization enthalpies increase for these elements because they have a higher number of d electrons.

Topic: Chemistry, d and f Block Elements, NEET
Why does the vapor pressure of a solution decrease when a non-volatile solute is added to the solvent?

Options:
A The solute molecules increase vaporization.
B The solute molecules reduce surface area.
C The solute molecules increase pressure.
D The solute molecules enhance the solute's volatility.

The correct answer is:
The solute molecules reduce surface area.

Solution:
The paragraph indicates that in a solution, the presence of solute molecules reduces the fraction of the surface area covered by solvent molecules, leading to a decrease in vapor pressure.

Topic: Chemistry, Solutions, NEET
Why does the white precipitate of silver halide become colored in the presence of dye eosin?

Options:
A Eosin undergoes a redox reaction with silver ions.
B Eosin adsorbs onto the surface of silver halide crystals.
C Eosin reduces the size of silver halide particles.
D Eosin forms a complex with silver ions.

The correct answer is:
Eosin adsorbs onto the surface of silver halide crystals.

Solution:
Correct Option is : (B)
Eosin adsorbs onto the surface of silver halide crystals.

Topic: Chemistry, Surface Chemistry, NEET
Why does very pure water have low conductivity?

Options:
A Due to the absence of ions
B Due to the presence of a high concentration of ions
C Due to the presence of a high concentration of electrons
D Due to the absence of electrons

The correct answer is:
Due to the absence of ions

Solution:
Very pure water has low conductivity because of the absence of ions, as stated in the paragraph.

Topic: Chemistry, Electrochemistry, NEET
Why does water covered with excessive algal growth become polluted?

Options:
A Growth of algae covers the water surface and reduces the concentration of oxygen in water. This leads to anaerobic conditions, commonly with accumulation of obnoxious decay and animal death.
B Algal growth enhances water quality by increasing oxygen levels.
C Algal growth in water has no impact on its pollution status.
D Algal growth promotes the removal of pollutants from water.

The correct answer is:
Growth of algae covers the water surface and reduces the concentration of oxygen in water. This leads to anaerobic conditions, commonly with accumulation of obnoxious decay and animal death.

Solution:
Correct Option is : (A)
Growth of algae covers the water surface and reduces the concentration of oxygen in water. This leads to anaerobic conditions, commonly with accumulation of obnoxious decay and animal death.

Topic: Chemistry, Environmental Chemistry, NEET
Why does water have a higher specific heat compared to other liquids?

Options:
A Due to its low density
B Due to the absence of hydrogen bonding
C Due to the presence of extensive hydrogen bonding
D Due to its colorless and tasteless nature

The correct answer is:
Due to the presence of extensive hydrogen bonding

Solution:
Water has a higher specific heat compared to other liquids because of the presence of extensive hydrogen bonding between its molecules.

Topic: Chemistry, Hydrogen, NEET
Why does water move from one system to another when in contact?

Options:
A Due to evaporation
B Due to a change in temperature
C Due to differences in water potential
D None of the above

The correct answer is:
Due to differences in water potential

Solution:
when two systems containing water are in contact, water will move from the system with higher water potential to the one with lower water potential. This is due to the random movement of water molecules and the transfer of energy.

Topic: Biology, Transport in Plants, NEET
Why does water on a clean glass surface tend to spread out while mercury on the same surface tends to form drops, also known as wetting behavior?

Options:
A Because water molecules have stronger cohesive forces than adhesive forces with the glass surface.
B Due to the higher density of mercury compared to water.
C It is a result of the temperature difference between water and mercury.
D Both water and mercury have similar adhesive forces with the glass surface.

The correct answer is:
Because water molecules have stronger cohesive forces than adhesive forces with the glass surface.

Solution:
Correct Option is : (A)
Because water molecules have stronger cohesive forces than adhesive forces with the glass surface.

Topic: Chemistry, Mechanical Properties of Fluids, NEET
Why does water show high boiling point as compared to hydrogen sulphide? Give reasons for your answer.

Options:
A Water molecules are polar and form stronger intermolecular forces.
B Hydrogen sulfide has a larger molecular size.
C Water molecules have higher kinetic energy.
D Water molecules have weaker intermolecular forces.

The correct answer is:
Water molecules are polar and form stronger intermolecular forces.

Solution:
Correct Option is : (A)
Water molecules are polar and form stronger intermolecular forces.

Topic: Chemistry, Hydrogen, NEET
Why does water with detergent dissolved in it result in small angles of contact?

Options:
A Because detergent increases the surface tension of water.
B Due to the reduced cohesive forces between water molecules.
C Because detergent molecules disrupt hydrogen bonding in water.
D Due to the enhanced capillary action caused by detergent reducing the angle of contact.

The correct answer is:
Due to the enhanced capillary action caused by detergent reducing the angle of contact.

Solution:
Correct Option is : (D)
Due to the enhanced capillary action caused by detergent reducing the angle of contact.

Topic: Chemistry, Mechanical Properties of Fluids, NEET
Why does white ZnO (s) becomes yellow upon heating?

Options:
A Because heating causes the decomposition of ZnO.
B Because white ZnO is impure and contains yellow impurities.
C Because F-centres are created when Zn2+ions (generated when ZnO is heated) and electrons move to interstitial sites
D Because ZnO naturally changes colour when exposed to heat.

The correct answer is:
Because F-centres are created when Zn2+ions (generated when ZnO is heated) and electrons move to interstitial sites

Solution:
Correct Option is : (C)
Because F-centres are created when Zn2+ions (generated when ZnO is heated) and electrons move to interstitial sites

Topic: Chemistry, Solid State, NEET
Why does Zn have the highest Eo value?

Options:
A The removal of an electron from the stable d10 configuration of Zn2+
B The half-filled t2g level of Zn2+
C The removal of an electron from the d5 configuration of Zn2+
D The stability of Zn3+ with a noble gas configuration

The correct answer is:
The removal of an electron from the stable d10 configuration of Zn2+

Solution:
The highest Eo value for Zn is due to the removal of an electron from the stable d10 configuration of Zn2+.

Topic: Chemistry, d and f Block Elements, NEET
Why doesn't boiling occur when a liquid is heated in a closed vessel?

Options:
A Because the vapor pressure decreases
B Because the liquid becomes more dense
C Because the temperature does not increase
D Because the liquid and vapor densities become the same

The correct answer is:
Because the vapor pressure decreases

Solution:
Boiling does not occur when a liquid is heated in a closed vessel because the vapor pressure increases, indicating that the vapor pressure must increase for boiling to take place.

Topic: Chemistry, States of Matter, NEET
Why don't all molecules in the atmosphere fall into the Earth like an apple falling from a tree?

Options:
A Because molecules are not affected by gravity.
B Due to the random thermal motion causing their velocity to be non-vertical.
C Molecules in the atmosphere are too small to be affected by gravity.
D Molecules are repelled by the Earth's gravitational force.

The correct answer is:
Due to the random thermal motion causing their velocity to be non-vertical.

Solution:
Correct Option is : (B)
Due to the random thermal motion causing their velocity to be non-vertical.

Topic: Chemistry, Gravitation, NEET
Why don't heavier elements of group 15, like phosphorus and arsenic, form pπ-pπ bonds like nitrogen?

Options:
A Due to high ionization enthalpy
B Due to high electronegativity
C Due to the absence of d orbitals
D Due to the large and diffuse atomic orbitals

The correct answer is:
Due to the large and diffuse atomic orbitals

Solution:
The paragraph states that heavier elements of group 15, like phosphorus and arsenic, do not form pπ-pπ bonds like nitrogen because their atomic orbitals are large and diffuse, preventing effective overlapping.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why H2S is more acidic than H2O?

Options:
A O-H bond is stronger than S-H bond
B O-H bond is weaker than S-H bond
C O is more electronegative than S
D None of these

The correct answer is:
O-H bond is stronger than S-H bond

Solution:
The acidity of hydrides of VI group elements increase from top to bottom as the bond strength X-H decrease from top to bottom
H2O<H2S<H2Se<H2Te

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Why has it been difficult to study the chemistry of radon?

Options:
A Radon is extremely rare and difficult to obtain.
B Radon is highly radioactive and has a short half-life.
C Radon is a noble gas and does not readily form compounds.
D Radon is highly reactive and forms unstable compounds.

The correct answer is:
Radon is a noble gas and does not readily form compounds.

Solution:
Correct Option is : (C)
Radon is a noble gas and does not readily form compounds.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why has the use of aluminum and its compounds for domestic purposes reduced considerably?

Options:
A Due to their high cost
B Because of their toxic nature
C Lack of availability
D Lack of durability

The correct answer is:
Because of their toxic nature

Solution:
The use of aluminum and its compounds for domestic purposes has reduced considerably because of their toxic nature.

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
Why have new biodegradable synthetic polymers been designed and developed?

Options:
A To increase the resistance of polymers to environmental degradation
B To create stronger and more durable polymers
C To reduce the cost of polymer production
D To address environmental concerns related to non-biodegradable polymers

The correct answer is:
To address environmental concerns related to non-biodegradable polymers

Solution:
New biodegradable synthetic polymers have been designed and developed to address environmental concerns related to the accumulation of non-biodegradable polymers in the environment.

Topic: Chemistry, Polymers, NEET
Why in the redox titration of KMnO4vs oxalic acid, we heat oxalic acid solution before starting the titration?

Options:
A Heating increases the solubility of oxalic acid in water.
B Oxalic acid is unstable at higher temperatures and needs to be stabilized.
C Heating is not required for this titration; it is done for safety reasons.
D The reaction between KMnO4and oxalic acid is very slow. By raising the temperature we can enhance the rate of reaction.

The correct answer is:
The reaction between KMnO4and oxalic acid is very slow. By raising the temperature we can enhance the rate of reaction.

Solution:
Correct Option is : (D)
The reaction between KMnO4and oxalic acid is very slow. By raising the temperature we can enhance the rate of reaction.

Topic: Chemistry, Chemical Kinetics, NEET
Why is a body with large reflectivity a poor emitter?

Options:
A Because it absorbs most of the incoming radiation.
B Because it emits radiation at a higher temperature.
C Because it has a low specific heat capacity.
D Because it is a good conductor of heat.

The correct answer is:
Because it absorbs most of the incoming radiation.

Solution:
Correct Option is : (A)
Because it absorbs most of the incoming radiation.

Topic: Chemistry, Thermal Properties of Matter, NEET
Why is a capsule advantageous to a bacterium?

Options:
A It protects the bacterium from desiccation.
B It provides means of locomotion.
C It allows bacterium to "hide" from host's immune system.
D It allows the bacterium to attach to the surface.

The correct answer is:
It allows bacterium to "hide" from host's immune system.

Solution:
S-strain bacteria or virulent bacteria are capsulated, made of polysaccharides and amino acids. It is tough and thick mucilage covering, providing protection to bacteria against host immune system.
Related Theory
The encapsulation makes bacteria more pathogenic. It protects bacteria from phagocytosis by macrophages. Capsule increases tolerance from desiccation. It helps bacteria adhere to surfaces. So capsule is the major determinant of virulence.

Topic: Biology, Biological Classification, NEET, NEET 2013 (Karnataka)
Why is a drop of liquid, under no external forces, always spherical in shape?

Options:
A Due to gravity pulling it into a sphere
B Because of the inherent spherical nature of liquid molecules
C The surface tension of the liquid minimizes its surface area
D It follows the principles of the Pythagorean theorem

The correct answer is:
The surface tension of the liquid minimizes its surface area

Solution:
Correct Option is : (C)
The surface tension of the liquid minimizes its surface area

Topic: Chemistry, Mechanical Properties of Fluids, NEET