Which of the following statements is/are correct regarding 'changes of state of matter'? A) A change of state of matter is a physical change. B) A change of state of matter is an irreversible change.
Changes of State are Physical
A change of state involves matter transitioning between solid, liquid, or gaseous forms (e.g., melting, freezing, boiling, condensation). These transformations alter the physical arrangement and energy of the molecules but not their fundamental chemical identity. Therefore, a change of state is classified as a physical change because the substance remains chemically the same before and after the transition. For instance, when ice (solid water) melts into liquid water, it is still H2O.
Statement A, "A change of state of matter is a physical change," is correct.
Irreversibility of State Changes
Statement B claims that a change of state is an irreversible change. This is generally incorrect. Most changes of state are readily reversible under different conditions. For example, water can freeze into ice (liquid to solid) and then melt back into water (solid to liquid) by simply adjusting the temperature. Similarly, water can boil into steam (liquid to gas) and condense back into water (gas to liquid).
Since changes of state are typically reversible, Statement B is incorrect.
Conclusion on Correct Statements
Based on the analysis:
- Statement A is correct (changes of state are physical changes).
- Statement B is incorrect (changes of state are typically reversible, not irreversible).
Therefore, only Statement A is correct.
Important Questions from States of Matter
A liquid is heated up to a certain temperature. Which one of the following situation would correspond to the boiling of the liquid?
Which one among the following oxides has the highest melting point?
Equal volume of all gases, when measured at the same temperature and pressure, contain an equal number of particles. Who proposed the above law?
Match List I with List II and select the correct answer using the code given below the Lists:
Code:List I (Noble gas)
List II (Use)
A. Argon
1. In lights for advertising display
B. Neon
2. Airport landing lights and in light houses
C. Krypton
3. Light in photographer’s flash gun
D. Xenon
4. In tungsten filament to last
Match List-I with List-II and select the correct answer using the code given below the Lists:
List I
(Process)
List II
(Type of change)
A. Heating of camphor
1. Chemical
B. Cooling of water vapor up to room temperature
2. Evaporation
C. Cooking an egg
3. Condensation
D. Formation of water vapor at room temperature.
4. Sublimation
