Question map
Which one of the following statements is not correct?
Explanation
Statement 4 is incorrect because the temperature at which a solid changes into a liquid is defined as the melting point [5]. The boiling point is the temperature at which a liquid changes into a gas. Regarding the other options: Conduction is most efficient in solids where particles are closely packed, less so in liquids, and very poor in gases due to large inter-particle distances [5]. Convection involves the actual movement of particles in fluids (liquids and gases) to carry heat energy [4]. Radiation is the transfer of heat energy via electromagnetic waves, which does not require a material medium and can occur through a vacuum [4]. Therefore, while statements 1, 2, and 3 accurately describe heat transfer mechanisms, statement 4 incorrectly identifies the phase change temperature.
Sources
- [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 7: Particulate Nature of Matter > Activity 7.3 : Let us find out > p. 103
- [5] https://gml.noaa.gov/outreach/info_activities/pdfs/TBI_heat_transfer.pdf
- [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 101
- [4] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 7: Particulate Nature of Matter > Ever heard of ... > p. 112