Q1: The temperature at which the magnetic property of iron disappears (i.e., it becomes non-magnetic) and its electrical conductivity & specific heat also changes, is called the 'Curie point', which is __________ °C.

ANS:A - 768

The temperature at which the magnetic property of iron disappears, known as the "Curie point," is approximately 768°C. Explanation: The Curie point is the temperature at which a material undergoes a phase transition from ferromagnetic to paramagnetic. In the case of iron, this transition occurs at approximately 768°C (1414°F) or 1041 K. At temperatures below the Curie point, iron exhibits ferromagnetic properties, meaning it can be magnetized and retains its magnetization when the magnetic field is removed. However, as the temperature increases beyond the Curie point, the alignment of magnetic domains within the material becomes disordered, causing the material to lose its ferromagnetic properties and become paramagnetic. Additionally, at the Curie point, iron also undergoes changes in its electrical conductivity and specific heat capacity. These changes are associated with alterations in the arrangement of atoms and electrons within the material as it transitions from the ferromagnetic phase to the paramagnetic phase. Therefore, the Curie point of iron is approximately 768°C.