Given below are two statements :
Statement I : Ferromagnetism is considered as an extreme form of paramagnetism.
Statement II : The number of unpaired electrons in a Cr2+ ion (Z = 24) is the same as that of a Nd3+ ion (Z = 60).
In the light of the above statements, choose the correct answer from the options given below :
Both Statement I and Statement II are false
Statement I is true but Statement II is false
Statement I is false but Statement II is true
Both Statement I and Statement II are true
Statement I is true but Statement II is false
Let us analyze the two statements step-by-step to arrive at the correct option.
Analysis of Statement I:
Paramagnetism is a property shown by substances that are weakly attracted by a magnetic field due to the presence of unpaired electrons. In paramagnetic materials, the individual atomic or molecular magnetic dipoles are randomly oriented in the absence of an external magnetic field. When an external magnetic field is applied, they align partially in the direction of the field.
Ferromagnetism is a phenomenon where certain materials (like iron, cobalt, nickel) exhibit extremely strong magnetic attraction and can be permanently magnetized. In ferromagnetic materials, the magnetic dipoles in small regions called domains are already aligned in the same direction even in the absence of an external magnetic field. When placed in a magnetic field, these domains align strongly in the direction of the field, leading to a very powerful magnetic effect. Therefore, ferromagnetism is indeed considered an extreme or highly ordered form of paramagnetism. Thus, Statement I is true.
Analysis of Statement II:
Let us find the number of unpaired electrons in a Cr2+ ion (Z = 24) and a Nd3+ ion (Z = 60).
For Chromium (Cr, Z = 24):
The ground-state electronic configuration of neutral Cr is:
[Ar] 3d5 4s1
When it loses two electrons to form a Cr2+ ion, the electrons are removed first from the 4s orbital and then from the 3d orbital. Thus, the configuration of Cr2+ is:
[Ar] 3d4 4s0
According to Hund's rule, the 4 electrons in the 3d subshell will occupy separate orbitals, resulting in:
Number of unpaired electrons in Cr2+ = 4
For Neodymium (Nd, Z = 60):
Neodymium is a lanthanide element. The ground-state electronic configuration of neutral Nd (Z = 60) relative to Xenon (Xe, Z = 54) is:
[Xe] 4f4 6s2
When it loses three electrons to form a Nd3+ ion, the electrons are removed first from the 6s orbital (two electrons) and then one electron from the 4f orbital. Thus, the configuration of Nd3+ is:
[Xe] 4f3
The 3 electrons in the 4f subshell will occupy separate orbitals, resulting in:
Number of unpaired electrons in Nd3+ = 3
Comparing the two values:
The number of unpaired electrons in Cr2+ (which is 4) is not equal to the number of unpaired electrons in Nd3+ (which is 3).
Therefore, Statement II is false.
Conclusion:
Since Statement I is true and Statement II is false, the correct option is "Statement I is true but Statement II is false".