JEE Chemistry 2026 Question with Solution

Given: Two statements are to be checked.

• Statement I: Count the pairs in which both ions are coloured.
• Statement II: Check whether $Ti^{4+}$ is the strongest reducing agent among $Th^{4+}$, $Ce^{4+}$, $Gd^{3+}$ and $Eu^{2+}$.

Find: Which option correctly describes the truth values of Statement I and Statement II.

Concept: Transition-metal ions are coloured when they have partially filled $d$-orbitals, that is, configurations from $d^1$ to $d^9$. Ions with $d^0$ or $d^{10}$ configurations are generally colourless.

Step 1: Check each pair in Statement I.

$$\text{Sc}^{3+} : d^0$$

So it is colourless, while

$$\text{Ti}^{3+} : d^1$$

is coloured. Therefore, this pair does not have both ions coloured.

$$\text{Mn}^{2+} : d^5$$

and

$$\text{Cr}^{2+} : d^4$$

Both are coloured, so this pair satisfies the condition.

$$\text{Cu}^{2+} : d^9$$

is coloured, while

$$\text{Zn}^{2+} : d^{10}$$

is colourless. Therefore, this pair does not satisfy the condition.

$$\text{Ni}^{2+} : d^8$$

is coloured, while

$$\text{Ti}^{4+} : d^0$$

is colourless. Therefore, this pair also does not satisfy the condition.

Only one pair, $[Mn^{2+},Cr^{2+}]$, has both ions coloured. Hence, Statement I is false.

Concept: A strong reducing agent is easily oxidised.

Step 2: Analyse Statement II.

$$\text{Ti}^{4+}$$

is already in a high oxidation state and tends to act as an oxidising agent, not a reducing agent.

$$\text{Eu}^{2+}$$

readily oxidises to $Eu^{3+}$ and is known to be a strong reducing agent.

Therefore, Statement II is false.

Conclusion: Both Statement I and Statement II are false. The correct option is C.