Chemistry Q74 – JEE-MAIN 2026

Home Chemistry Structure of AtomQuestion #599

Number of paramagnetic ions among the following d- and f-block metal ions is _______.

M n^{2 +}

C u^{2 +}

Z n^{2 +}

Y b^{2 +}

S c^{3 +}

L a^{3 +}

G d^{3 +}

L u^{3 +}

T i^{4 +}

C e^{4 +}

\ (Atomic number of

M n = 25

C u = 29

Z n = 30

Y b = 70

S c = 21

L a = 57

G d = 64

L u = 71

T i = 22

C e = 58

)

Enter Calculated Numerical Value:

Clue 1 of 3: Paramagnetism Definition

Paramagnetic substances are attracted to magnetic fields due to the presence of unpaired electrons in their atomic or molecular orbitals.

🧠 Full Solution Path

Step 1: Determine Electronic Configurations of Ions✦ Active

First, write the ground state electronic configuration for each neutral atom using the given atomic numbers. Then, remove electrons according to the charge of the ion, remembering that for transition metals, electrons are removed from the outermost s-orbital before the d-orbital, and for lanthanides, from the s-orbital, then d-orbital (if present), then f-orbital.

M n (Z = 25) : [A r] 3 d^{5} 4 s^{2} ⟹ M n^{2 +} : [A r] 3 d^{5} {(5 unpaired e}^{-})

C u (Z = 29) : [A r] 3 d^{10} 4 s^{1} ⟹ C u^{2 +} : [A r] 3 d^{9} {(1 unpaired e}^{-})

Z n (Z = 30) : [A r] 3 d^{10} 4 s^{2} ⟹ Z n^{2 +} : [A r] 3 d^{10} {(0 unpaired e}^{-})

Y b (Z = 70) : [X e] 4 f^{14} 6 s^{2} ⟹ Y b^{2 +} : [X e] 4 f^{14} {(0 unpaired e}^{-})

S c (Z = 21) : [A r] 3 d^{1} 4 s^{2} ⟹ S c^{3 +} : [A r] {(0 unpaired e}^{-})

L a (Z = 57) : [X e] 5 d^{1} 6 s^{2} ⟹ L a^{3 +} : [X e] {(0 unpaired e}^{-})

G d (Z = 64) : [X e] 4 f^{7} 5 d^{1} 6 s^{2} ⟹ G d^{3 +} : [X e] 4 f^{7} {(7 unpaired e}^{-})

L u (Z = 71) : [X e] 4 f^{14} 5 d^{1} 6 s^{2} ⟹ L u^{3 +} : [X e] 4 f^{14} {(0 unpaired e}^{-})

T i (Z = 22) : [A r] 3 d^{2} 4 s^{2} ⟹ T i^{4 +} : [A r] {(0 unpaired e}^{-})

C e (Z = 58) : [X e] 4 f^{1} 5 d^{1} 6 s^{2} ⟹ C e^{4 +} : [X e] {(0 unpaired e}^{-})

💡 Teacher's Secret Hint

Remember the exceptions in electronic configurations for elements like Cr and Cu, and the order of electron removal for ions.

Step 2: Identify Paramagnetic Ions○ Expand

An ion is paramagnetic if it has one or more unpaired electrons. Based on the electronic configurations determined in Step 1, the ions with unpaired electrons are:

M n^{2 +} (3 d^{5}) : 5 unpaired electrons

C u^{2 +} (3 d^{9}) : 1 unpaired electron

G d^{3 +} (4 f^{7}) : 7 unpaired electrons

Step 3: Count the Total Number of Paramagnetic Ions○ Expand

Counting these ions, we find there are 3 paramagnetic ions.

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Chemistry Question 74 – JEE-MAIN 2026

Clue 1 of 3: Paramagnetism Definition

🧠 Full Solution Path