NEETChemistryStructure of Atom
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): All five 3 d orbitals of an atom have identical shapes, which is the reason for their equal energy in the free state. Reason (R): In an isolated multi-electron atom, all the five 3 d orbitals are degenerate. In the light of the above statements, choose the most appropriate answer from the options g
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
D. (A) is false but (R) is true
Step-by-step solution
Assertion (A) is false because the shapes of all five 3 d orbitals are not identical. The first four d-orbitals ( d_ xy , d_ yz , d_ zx , d_ x^2-y^2 ) have similar four-lobed shapes, but the d_ z^2 orbital has a uniquely different shape consisting of two lobes along the z-axis and a doughnut-shaped electron cloud in the xy plane. Reason (R) is true because in an isolated atom (free state), all five 3 d orbitals belong to the same subshell and have the exact same energy, meaning they are degenerate. Thus, (A) is fal