NEET UG 2010 — Chemistry Inorganic Chemistry

2010mcqeasy

Which of the following ions will exhibit colour in aqueous solutions ?

Official previous-year question

Held on 30 Apr 2010 · Verified 9 Jul 2026.

Options

A
$\mathrm{La}^{3+}(\mathrm{Z}=57)$
B
$\mathrm{Ti}^{3+}(\mathrm{Z}=22)$
C
$\mathrm{Lu}^{3+}(\mathrm{Z}=71)$
D
$\mathrm{Sc}^{3+}(\mathrm{Z}=21)$

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Solution

Key Idea:- Colour is obtained as a consequence of $d-d($ or $f-f)$ transition, and for $d-d$ (or $f-f)$ transition, presence of unpaired electrons is the necessary condition. $\begin{gathered} \mathrm{La}^{3+}(\mathrm{Z}=57)=[\mathrm{Xe}] 4 \mathrm{f}^0 5 \mathrm{~d}^0 6 \mathrm{~s}^0 \\ \text { (no unpaired electron) } \\ \mathrm{Ti}^{3+}(\mathrm{Z}=22)=[\mathrm{Ar}] 3 \mathrm{~d}^1 4 \mathrm{~s}^0 \\ \text { (one unpaired electron) } \\ \mathrm{Lu}^{3+}(\mathrm{Z}=71)=[\mathrm{Xe}] 4 \mathrm{f}^{14} 5 \mathrm{~d}^0 6 \mathrm{~s}^0 \\ \text { (no unpaired electron) } \\ \mathrm{Sc}^{3+}(\mathrm{Z}=21)=[\mathrm{Ar}] 3 \mathrm{~d}^0 4 \mathrm{~s}^0 \end{gathered}$ (no unpaired electron) Hence, only $\mathrm{Ti}^{3+}$ will exhibit colour in aqueous solution.

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NEET UG 2010 — Chemistry Inorganic Chemistry

2010mcqeasy

Which of the following ions will exhibit colour in aqueous solutions ?

Official previous-year question

Held on 30 Apr 2010 · Verified 9 Jul 2026.

Options

A
$\mathrm{La}^{3+}(\mathrm{Z}=57)$
B
$\mathrm{Ti}^{3+}(\mathrm{Z}=22)$
C
$\mathrm{Lu}^{3+}(\mathrm{Z}=71)$
D
$\mathrm{Sc}^{3+}(\mathrm{Z}=21)$

Did you get this right?

Solution

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NEET UG Inorganic Chemistry in other years

Keep practicing Inorganic Chemistry

Work through every NEET UG Inorganic Chemistry PYQ, year by year.

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NEET UG 2010 — Chemistry Inorganic Chemistry

Options

Did you get this right?

Solution

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NEET UG Inorganic Chemistry in other years

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Physical Chemistry

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NEET UG 2010 — Chemistry Inorganic Chemistry

Options

Did you get this right?

Solution

Your note

NEET UG Inorganic Chemistry in other years

More NEET UG Inorganic Chemistry questions

Other Chemistry topics for NEET UG

Physical Chemistry

Organic Chemistry

Keep practicing Inorganic Chemistry