Solvation MCQs With Answer

Solvation MCQs With Answer is an essential collection for B. Pharm students mastering solvent–solute interactions, solubility principles, and hydration phenomena in pharmaceutical systems. This focused set covers solvation definition, solvation shells, solvent polarity, dielectric constant, enthalpy and entropy of solution, ion solvation, hydrogen bonding, and implications for drug formulation and stability. Each question is designed to deepen understanding of how solvation influences drug dissolution, bioavailability, and excipient selection, with practical examples relevant to dosage form design. Ideal for exam preparation and concept reinforcement, these targeted practice items emphasize both theory and pharmaceutical applications. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the definition of solvation?

• The process of a solute chemically reacting to form a new compound
• The process of surrounding solute particles with solvent molecules
• The phase transition from solid to gas without passing through liquid
• The formation of covalent bonds between solute and solvent

Correct Answer: The process of surrounding solute particles with solvent molecules

Q2. Which term specifically describes solvation by water?

• Hydration
• Ionization
• Hydrogenation
• Hydrolysis

Correct Answer: Hydration

Q3. What primarily determines the extent of solvation in polar solvents?

• Van der Waals forces only
• Solvent polarity and dipole–solute interactions
• Covalent bonding between solvent and solute
• Molecular weight of the solvent

Correct Answer: Solvent polarity and dipole–solute interactions

Q4. Which property of a solvent measures its ability to reduce electrostatic forces between charged particles?

• Surface tension
• Dielectric constant
• Viscosity
• Boiling point

Correct Answer: Dielectric constant

Q5. The formation of a solvation shell typically leads to which of the following for ionic solutes?

• Increased lattice energy
• Stabilization of ions in solution
• Precipitation of the solute
• Covalent bond formation between ions

Correct Answer: Stabilization of ions in solution

Q6. Which interaction is most important in the solvation of a neutral polar molecule?

• Hydrogen bonding and dipole–dipole interactions
• Pi–pi stacking
• Metal coordination
• Chelation

Correct Answer: Hydrogen bonding and dipole–dipole interactions

Q7. What is the effect of solvation on the free energy of a solute when dissolution is favorable?

• Free energy increases
• Free energy remains unchanged
• Free energy decreases
• Free energy becomes infinite

Correct Answer: Free energy decreases

Q8. Which term describes the enthalpy change when one mole of solute dissolves in a large amount of solvent at constant pressure?

• Heat of vaporization
• Heat of fusion
• Enthalpy of solution (heat of solution)
• Activation enthalpy

Correct Answer: Enthalpy of solution (heat of solution)

Q9. A negative enthalpy of solvation indicates what about the solute–solvent interactions?

• They are endothermic and weak
• They are exothermic and favorable
• They prevent solvation entirely
• They cause immediate precipitation

Correct Answer: They are exothermic and favorable

Q10. Which factor increases solvation of a gas in a liquid at constant temperature?

• Decrease in gas partial pressure above the liquid
• Increase in temperature (for gases that obey Henry’s law only)
• Increase in solvent–gas attractive interactions
• Decreasing solvent polarity for polar gases

Correct Answer: Increase in solvent–gas attractive interactions

Q11. In pharmaceutical formulations, why is solvation important for drug bioavailability?

• Solvation prevents drugs from dissolving in GI fluids
• Solvation affects dissolution rate and drug availability for absorption
• Solvation increases drug molecular weight
• Solvation always causes drug degradation

Correct Answer: Solvation affects dissolution rate and drug availability for absorption

Q12. Which solvent property would you consider to improve solubility of an ionizable drug in its ionized form?

• Lower dielectric constant
• Higher dielectric constant
• Lower viscosity only
• Higher boiling point only

Correct Answer: Higher dielectric constant

Q13. What role do cosolvents (e.g., ethanol) play in solvation of poorly soluble drugs?

• Cosolvents always precipitate drugs
• Cosolvents decrease solvent polarity to improve solubility of nonpolar drugs
• Cosolvents form covalent bonds with drugs
• Cosolvents remove solvation shells entirely

Correct Answer: Cosolvents decrease solvent polarity to improve solubility of nonpolar drugs

Q14. Which measurement indicates the extent of solvation for electrolytes in solution?

• Osmotic pressure only
• Conductivity and activity coefficients
• Color change of solution
• Melting point elevation

Correct Answer: Conductivity and activity coefficients

Q15. The primary driving force for hydrophobic hydration around nonpolar solutes is:

• Formation of strong hydrogen bonds between water and the nonpolar solute
• Entropy increase due to ordered water structure
• Entropy decrease due to structured water cages around nonpolar solutes
• Covalent bond formation between water and solute

Correct Answer: Entropy decrease due to structured water cages around nonpolar solutes

Q16. What is meant by the term ‘solvation number’?

• The number of solute molecules per solvent molecule
• The number of solvent molecules in the immediate solvation shell around a solute
• The number of ions produced upon dissolution
• The mole fraction of solvent in solution

Correct Answer: The number of solvent molecules in the immediate solvation shell around a solute

Q17. Which spectroscopic method is commonly used to study solvation shells and hydrogen bonding in solution?

• Nuclear magnetic resonance (NMR) spectroscopy
• X-ray crystallography only
• Mass spectrometry only
• Polarimetry only

Correct Answer: Nuclear magnetic resonance (NMR) spectroscopy

Q18. In ion solvation, what is the Born solvation energy model used to estimate?

• Entropy of mixing
• Electrostatic contribution to solvation free energy of an ion
• Rate of chemical reaction in solution
• Viscosity of electrolyte solutions

Correct Answer: Electrostatic contribution to solvation free energy of an ion

Q19. Which of the following increases ionic solubility in water?

• Lower solvent dielectric constant
• Higher temperature for exothermic dissolution processes
• Presence of hydrophobic cosolvents
• Formation of insoluble complexes

Correct Answer: Higher temperature for exothermic dissolution processes

Q20. Which phenomenon describes the reduced effective concentration of a solute due to solute–solvent interactions?

• Osmosis
• Activity (and activity coefficient)
• Crystallization
• Polymorphism

Correct Answer: Activity (and activity coefficient)

Q21. Which solvent would better solvate an ionic drug: water or hexane?

• Hexane
• Water
• Both equally
• Neither

Correct Answer: Water

Q22. What happens to hydration shells when ionic strength of the solution increases significantly?

• Hydration shells become stronger and always increase solubility
• Hydration shells can be disrupted by ion pairing and screening effects
• Hydration shells turn into covalent bonds
• Hydration shells completely disappear and precipitate forms immediately

Correct Answer: Hydration shells can be disrupted by ion pairing and screening effects

Q23. Which is an example of specific solute–solvent interaction important in solvation?

• London dispersion exclusively
• Hydrogen bonding between solute and solvent
• Bulk modulus changes
• Crystal lattice matching

Correct Answer: Hydrogen bonding between solute and solvent

Q24. Which statement best describes ‘preferential solvation’?

• Solute is equally surrounded by all solvent components in a mixture
• Solute is surrounded preferentially by one solvent component over another in a mixed solvent system
• Solute is never solvated in mixed solvents
• Preferential solvation only occurs in pure solvents

Correct Answer: Solute is surrounded preferentially by one solvent component over another in a mixed solvent system

Q25. How does temperature generally affect solvation of solids in liquids?

• Temperature has no effect on solvation
• Temperature effect depends on enthalpy of dissolution; solubility may increase or decrease
• Solubility always decreases with temperature
• Solubility always increases with temperature

Correct Answer: Temperature effect depends on enthalpy of dissolution; solubility may increase or decrease

Q26. Which term refers to the energy required to separate solute particles from each other before solvation?

• Lattice energy or cohesive energy
• Ionization energy of solvent
• Activation energy of diffusion
• Boiling point elevation

Correct Answer: Lattice energy or cohesive energy

Q27. In drug formulation, surfactants enhance solvation by:

• Forming micelles that solubilize hydrophobic drugs
• Decreasing solvent polarity dramatically to precipitate drugs
• Breaking covalent bonds in drugs
• Increasing crystal lattice energy

Correct Answer: Forming micelles that solubilize hydrophobic drugs

Q28. What is ion pairing in the context of solvation?

• Formation of covalent bonds between ions
• Oppositely charged ions being closely associated, reducing their effective solvation
• Complete separation of ions by solvent
• Neutralization of solvent polarity

Correct Answer: Oppositely charged ions being closely associated, reducing their effective solvation

Q29. Which solvent characteristic favors stronger hydrogen bonding with solute molecules?

• Low ability to donate hydrogen bonds
• High hydrogen-bond donor and acceptor capacity
• High molecular weight without polar groups
• Low dipole moment

Correct Answer: High hydrogen-bond donor and acceptor capacity

Q30. Which is an example of a kosmotropic ion effect on solvation?

• Disruption of water structure increasing solute hydrophobicity
• Structuring water and stabilizing hydration shells around solutes
• Complete removal of solvent molecules from solute
• Increasing volatility of solvent

Correct Answer: Structuring water and stabilizing hydration shells around solutes

Q31. Solvent–solute interactions that lower system entropy most are associated with which solvation phenomenon?

• Hydrophobic hydration around nonpolar solutes
• Ideal mixing without interactions
• Complete solute vaporization
• Formation of gaseous products

Correct Answer: Hydrophobic hydration around nonpolar solutes

Q32. Which parameter is directly related to the stabilization of ions by solvation in water?

• pKa of water
• Dielectric constant of water
• Surface tension only
• Viscosity only

Correct Answer: Dielectric constant of water

Q33. What effect does solvation have on ionic mobility in solution?

• Solvation always increases ionic mobility
• Solvation can decrease mobility by increasing effective ion size due to solvation shell
• Solvation transforms ions into neutral molecules
• Solvation eliminates ionic charge

Correct Answer: Solvation can decrease mobility by increasing effective ion size due to solvation shell

Q34. Which of the following best describes ‘desolvation’ in a biochemical context?

• Process of increasing the solvation shell size around biomolecules
• Removal of solvent molecules from solute surfaces, often required for binding or crystallization
• Creation of new covalent bonds with solvent
• Hydrolysis of solvent molecules

Correct Answer: Removal of solvent molecules from solute surfaces, often required for binding or crystallization

Q35. When a drug binds to a protein target, what solvation-related process often contributes to binding affinity?

• Complete increase in solvation of both drug and protein
• Desolvation of binding surfaces and release of structured water, contributing to entropy changes
• Formation of solvent covalent bonds to the drug
• Permanent ionization of the protein

Correct Answer: Desolvation of binding surfaces and release of structured water, contributing to entropy changes

Q36. Which ion is more strongly solvated in water: Na+ or Cs+?

• Cs+
• Na+
• Both equally
• Neither is solvated

Correct Answer: Na+

Q37. Which process competes with solvation when salts are dissolved in water?

• Crystal lattice separation (overcoming lattice energy) and ion hydration
• Formation of covalent bonds between ions
• Polymerization of solvent molecules
• Combustion reactions

Correct Answer: Crystal lattice separation (overcoming lattice energy) and ion hydration

Q38. For polar aprotic solvents (e.g., acetone), which solvation characteristic is typical?

• Strong hydrogen-bond donation to anions
• Poor hydrogen-bond donation but good solvation of cations via dipole interactions
• Complete insolubility of ionic compounds
• High dielectric constant identical to water

Correct Answer: Poor hydrogen-bond donation but good solvation of cations via dipole interactions

Q39. Which experimental technique can quantify hydration numbers around ions?

• UV-visible spectroscopy exclusively
• Neutron scattering and dielectric relaxation studies
• Thin-layer chromatography
• Refractive index measurement only

Correct Answer: Neutron scattering and dielectric relaxation studies

Q40. Which of the following increases when solute–solvent hydrogen bonding is strong?

• Vapor pressure of solution
• Boiling point elevation of the solution
• Rate of sublimation
• Freezing point of pure solvent

Correct Answer: Boiling point elevation of the solution

Q41. Solvation dynamics refers to:

• Static structure of solid crystals only
• Time-dependent reorganization of solvent molecules around a solute after a perturbation
• Formation of covalent bonds in solution
• Permanent dehydration of biomolecules

Correct Answer: Time-dependent reorganization of solvent molecules around a solute after a perturbation

Q42. Which factor most strongly affects solvation in mixed solvent systems?

• The chemical potential and preferential interactions of each solvent component with the solute
• Only the vapor pressure of the first solvent
• Only the temperature of the system
• Presence of inert gas above the solution

Correct Answer: The chemical potential and preferential interactions of each solvent component with the solute

Q43. In the context of drug crystallization from solution, what role does solvation play?

• No role in crystallization
• Solvation influences nucleation, growth kinetics, and polymorph selection
• Solvation only affects color of the crystals
• Solvation prevents any crystal formation always

Correct Answer: Solvation influences nucleation, growth kinetics, and polymorph selection

Q44. Which statement about solvation and pKa of a drug is correct?

• Solvation cannot influence pKa values
• Solvation and solvent polarity can shift apparent pKa values by stabilizing ionized or unionized forms
• Only temperature controls pKa
• pKa is purely intrinsic and independent of environment

Correct Answer: Solvation and solvent polarity can shift apparent pKa values by stabilizing ionized or unionized forms

Q45. Which of the following is true about solvent reorganization energy during electron transfer in solution?

• It is irrelevant to reaction kinetics
• Solvent reorganization energy influences activation barrier for electron transfer
• It only affects solid-state reactions
• It always equals zero

Correct Answer: Solvent reorganization energy influences activation barrier for electron transfer

Q46. Which technique helps observe ultrafast solvation dynamics?

• Steady-state UV spectroscopy
• Femtosecond time-resolved spectroscopy
• Classical titration
• Room-temperature polarimetry

Correct Answer: Femtosecond time-resolved spectroscopy

Q47. Which describes the effect of adding salt to a solution on solvation of nonpolar molecules (salting-out)?

• Salt increases solubility of nonpolar molecules always
• Salt can decrease solubility of nonpolar molecules by strengthening water structure and reducing available solvent for solute
• Salt forms covalent complexes with nonpolar molecules
• Salt removes hydration shells and causes immediate boiling

Correct Answer: Salt can decrease solubility of nonpolar molecules by strengthening water structure and reducing available solvent for solute

Q48. Which factor is critical when selecting a solvent for drug extraction based on solvation?

• Solvent odor only
• Solvent polarity, solute compatibility, and safety/toxicity
• Genetic sequence of the drug
• Color of the solvent

Correct Answer: Solvent polarity, solute compatibility, and safety/toxicity

Q49. Which statement about solvent polarity and drug partitioning is correct?

• Nonpolar solvents always favor ionized drug partitioning
• Polar solvents favor dissolution/solvation of polar or ionized drugs, affecting partition coefficients
• Polarity has no effect on partitioning
• Partitioning depends solely on stirring speed

Correct Answer: Polar solvents favor dissolution/solvation of polar or ionized drugs, affecting partition coefficients

Q50. In computational studies of solvation, which models are commonly used?

• Implicit continuum solvent models and explicit solvent molecular dynamics
• Only ideal gas models
• Solid-state lattice models exclusively
• None; solvation cannot be modeled computationally

Correct Answer: Implicit continuum solvent models and explicit solvent molecular dynamics

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com