Introduction: Understanding the states of matter is essential for B.Pharm students, as solid, liquid, gas and plasma behaviors influence drug design, formulation, stability and delivery. This guide on States of matter MCQs With Answer focuses on phase transitions, intermolecular forces, crystallinity, polymorphism, glass transition, vapor pressure, solubility and thermodynamic principles relevant to pharmaceuticals. Clear concepts about amorphous versus crystalline forms, particle size effects, surface energy and rheological properties improve formulation decisions and quality control. These targeted MCQs reinforce theoretical foundations and practical implications in drug development, stability testing and processing. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which state of matter has a definite volume but no definite shape?
- Gas
- Liquid
- Solid
- Plasma
Correct Answer: Liquid
Q2. Which intermolecular force is strongest in determining the high melting point of ionic solids?
- Hydrogen bonding
- London dispersion forces
- Ionic bonding (electrostatic attraction)
- Dipole–dipole interactions
Correct Answer: Ionic bonding (electrostatic attraction)
Q3. Polymorphism in a drug refers to:
- The presence of different salts of the drug
- The ability to form hydrates only
- The occurrence of the drug in different crystalline forms
- The drug’s solubility in various solvents
Correct Answer: The occurrence of the drug in different crystalline forms
Q4. Which process is direct transition from solid to gas without passing through the liquid state?
- Sublimation
- Condensation
- Evaporation
- Fusion
Correct Answer: Sublimation
Q5. The glass transition temperature (Tg) is most relevant to which type of pharmaceutical material?
- Crystalline salts
- Amorphous solids
- Gaseous preservatives
- Metallic implants
Correct Answer: Amorphous solids
Q6. Which property increases when particle size decreases, affecting dissolution rate?
- Density
- Surface area
- Melting point
- Polymorphic stability
Correct Answer: Surface area
Q7. Which law relates pressure and volume of a gas at constant temperature?
- Charles’s law
- Avogadro’s law
- Boyle’s law
- Henry’s law
Correct Answer: Boyle’s law
Q8. Vapor pressure of a liquid is most directly influenced by:
- External magnetic field
- Intermolecular forces and temperature
- Color of container
- Molecular weight only
Correct Answer: Intermolecular forces and temperature
Q9. In a phase diagram, the triple point represents:
- The temperature and pressure where gas and liquid coexist only
- The conditions where solid, liquid and gas coexist
- The point of maximum solubility
- A metastable polymorphic form
Correct Answer: The conditions where solid, liquid and gas coexist
Q10. Which term describes solids lacking long-range molecular order?
- Crystalline
- Polymeric
- Amorphous
- Colloidal
Correct Answer: Amorphous
Q11. Which measurement is commonly used to characterize crystallinity in pharmaceutical solids?
- NMR spectroscopy for liquids
- X-ray powder diffraction (XRPD)
- UV-visible absorption
- pH titration
Correct Answer: X-ray powder diffraction (XRPD)
Q12. Critical temperature is defined as:
- The temperature below which gas can be liquefied by pressure alone
- The temperature at which solid melts at 1 atm
- The temperature above which liquid and gas phases are indistinguishable
- The temperature for maximum solubility
Correct Answer: The temperature above which liquid and gas phases are indistinguishable
Q13. Which phenomenon explains the tendency of liquids to minimize surface area?
- Viscosity
- Surface tension
- Diffusion coefficient
- Osmotic pressure
Correct Answer: Surface tension
Q14. Lyophilization (freeze-drying) relies on which phase change?
- Condensation
- Sublimation
- Melting
- Recrystallization
Correct Answer: Sublimation
Q15. Which gas law relates volume and temperature at constant pressure?
- Boyle’s law
- Charles’s law
- Dalton’s law
- Graham’s law
Correct Answer: Charles’s law
Q16. Hygroscopicity in solids refers to the tendency to:
- Undergo polymorphic transition
- Absorb moisture from the environment
- Crystallize spontaneously
- Evaporate rapidly
Correct Answer: Absorb moisture from the environment
Q17. Which property is lowered in amorphous forms compared to crystalline forms, often increasing solubility?
- Chemical potency
- Thermodynamic stability
- Melting point and lattice energy
- Optical rotation
Correct Answer: Melting point and lattice energy
Q18. Adsorption at a solid surface is primarily governed by:
- Bulk viscosity
- Surface area and surface energy
- Color of the solid
- Atmospheric pressure only
Correct Answer: Surface area and surface energy
Q19. Which transition involves conversion of liquid to vapor at temperatures below the boiling point?
- Freezing
- Evaporation
- Sublimation
- Condensation
Correct Answer: Evaporation
Q20. In solid dispersions, improving drug bioavailability is often achieved by:
- Increasing crystallinity
- Decreasing surface area
- Stabilizing the amorphous state
- Reducing dissolution rate
Correct Answer: Stabilizing the amorphous state
Q21. Which of the following describes a colloidal state relevant to suspensions?
- Particles > 1 mm
- Particles in the range 1–1000 nm with Brownian motion
- Complete molecular dissolution
- Pure crystalline lattice
Correct Answer: Particles in the range 1–1000 nm with Brownian motion
Q22. A metastable polymorph typically has:
- Lower solubility than the stable form
- Higher thermodynamic stability than the stable form
- Higher apparent solubility but converts to the stable form over time
- No practical relevance in formulations
Correct Answer: Higher apparent solubility but converts to the stable form over time
Q23. Which process is commonly used to characterize vapor pressure–temperature relationship?
- DSC (Differential Scanning Calorimetry)
- TGA (Thermogravimetric Analysis)
- Clausius–Clapeyron equation application
- IR spectroscopy
Correct Answer: Clausius–Clapeyron equation application
Q24. Diffusion of drug molecules in a liquid medium is best described by:
- Fick’s laws of diffusion
- Raoult’s law
- Henry’s law
- Le Chatelier’s principle
Correct Answer: Fick’s laws of diffusion
Q25. Which factor does NOT significantly affect the melting point of a crystalline drug?
- Impurities
- Crystal lattice energy
- Atmospheric composition of inert gas
- Polymorphic form
Correct Answer: Atmospheric composition of inert gas
Q26. In a gas mixture, Dalton’s law pertains to:
- Partial pressures of components
- Viscosity of the mixture
- Solubility of solids
- Surface tension effects
Correct Answer: Partial pressures of components
Q27. Which rheological behavior is common in suspensions used in pharmaceuticals?
- Newtonian (constant viscosity)
- Plastic or pseudoplastic (shear-thinning)
- Explosive expansion
- Superconductivity
Correct Answer: Plastic or pseudoplastic (shear-thinning)
Q28. The phenomenon where two immiscible liquids form a single phase under certain conditions is called:
- Sublimation
- Miscibility or critical mixing
- Crystallization
- Solidification
Correct Answer: Miscibility or critical mixing
Q29. The highest temperature at which a crystal and its melt can coexist is called:
- Boiling point
- Melting point (fusion point)
- Glass transition
- Triple point
Correct Answer: Melting point (fusion point)
Q30. Which analytical method measures glass transition temperature?
- HPLC
- DSC (Differential Scanning Calorimetry)
- Mass spectrometry
- Polarimetry
Correct Answer: DSC (Differential Scanning Calorimetry)
Q31. In lyophilized pharmaceuticals, maintaining amorphous state can improve:
- Chemical degradation rate
- Physical stability in humid conditions
- Reconstitution time and solubility
- Bulk density only
Correct Answer: Reconstitution time and solubility
Q32. Which statement about plasma (ionized gas) is true in pharmaceutical context?
- Plasma is commonly used as a solvent
- Plasma contains free ions and electrons and is rarely encountered in routine pharmaceutics
- Plasma is identical to liquid state
- Plasma has fixed shape
Correct Answer: Plasma contains free ions and electrons and is rarely encountered in routine pharmaceutics
Q33. Moisture sorption isotherms are important to predict:
- Color changes under light
- Water uptake and storage stability
- Drug molecular weight
- Acid–base titration curves
Correct Answer: Water uptake and storage stability
Q34. Which form typically exhibits higher free energy and higher dissolution rate?
- Stable crystalline form
- Polymorph with lower energy
- Amorphous form
- Hydrate with strong lattice
Correct Answer: Amorphous form
Q35. In gas diffusion through membranes, flux is driven primarily by:
- Concentration gradient
- Surface tension only
- Electrical conductivity
- Color of the membrane
Correct Answer: Concentration gradient
Q36. Which is an example of a crystalline pharmaceutical effect important for tablet compression?
- Amorphous relaxation
- Crystal habit and interparticulate friction
- Gas solubility
- Plasma conductivity
Correct Answer: Crystal habit and interparticulate friction
Q37. Vaporization that occurs throughout the liquid at boiling point is called:
- Evaporation
- Boiling
- Sublimation
- Adsorption
Correct Answer: Boiling
Q38. Which phenomenon can cause an amorphous drug to crystallize during storage?
- Low humidity and low temperature only
- Exposure to moisture or thermal stress
- Presence of antioxidants only
- Packaging in inert gas always prevents it
Correct Answer: Exposure to moisture or thermal stress
Q39. Raoult’s law is applicable to which type of mixtures?
- Ideal solutions for vapor pressure lowering
- Colloidal suspensions
- Pure solids only
- Nonvolatile solid mixtures
Correct Answer: Ideal solutions for vapor pressure lowering
Q40. Which parameter is crucial for predicting aerosol behavior of inhalation drugs?
- Color index
- Particle aerodynamic diameter
- Glass transition temperature only
- Electrical polarity only
Correct Answer: Particle aerodynamic diameter
Q41. Which is NOT a typical effect of high crystallinity on drug performance?
- Lower solubility
- Higher mechanical strength
- Faster dissolution than amorphous
- Lower chemical reactivity
Correct Answer: Faster dissolution than amorphous
Q42. In suspension stability, zeta potential measures:
- Particle color
- Surface charge and electrostatic repulsion
- Thermal conductivity
- pH buffer capacity
Correct Answer: Surface charge and electrostatic repulsion
Q43. Which thermodynamic quantity determines spontaneity of phase transition at constant temperature and pressure?
- Entropy alone
- Enthalpy alone
- Gibbs free energy
- Heat capacity
Correct Answer: Gibbs free energy
Q44. Supersaturation is important in crystallization because it:
- Promotes nucleation and crystal growth
- Prevents any phase change
- Reduces solute concentration
- Eliminates polymorphism
Correct Answer: Promotes nucleation and crystal growth
Q45. Which technique is used to observe crystal habit and morphology?
- Light microscopy or polarized light microscopy
- UV spectroscopy
- Gas chromatography
- pH meter
Correct Answer: Light microscopy or polarized light microscopy
Q46. A supercooled liquid is best described as:
- A gas under high pressure
- A liquid cooled below its freezing point without crystallizing
- A crystalline solid heated above melting point
- An ionized plasma
Correct Answer: A liquid cooled below its freezing point without crystallizing
Q47. Which factor most directly affects vapor-liquid equilibrium in closed containers?
- Container color
- Temperature and liquid volatility
- Amount of dissolved solid only
- pH of the liquid
Correct Answer: Temperature and liquid volatility
Q48. Which state of matter is characterized by long-range order and fixed lattice positions?
- Amorphous solid
- Crystalline solid
- Liquid crystal only
- Gaseous phase
Correct Answer: Crystalline solid
Q49. The term hygroscopic deliquescent refers to a solid that:
- Releases water under humidity
- Absorbs moisture and dissolves to form a solution
- Is completely insoluble in water
- Turns into gas on exposure to air
Correct Answer: Absorbs moisture and dissolves to form a solution
Q50. Which physical parameter is most useful to predict powder flow in tableting?
- Melting point
- Bulk and tapped density (compressibility index)
- Optical rotation
- Boiling point
Correct Answer: Bulk and tapped density (compressibility index)
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.
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