JEE Main 2026 — Chemistry Inorganic Chemistry

2026mcqmedium

Which of the following sets includes all the species that will change the orange colour of $K_2Cr_2O_7$ in acidic medium?

Official previous-year question

Held on 2 Apr 2026 · Verified 6 Jul 2026.

Options

A
$Fe^{2+}, Sn^{2+}, I^-, S^{2-}$
B
$S^{2-}, Fe^{3+}, I^-, C_2O_4^{2-}$
C
$Fe^{2+}, NO_2^-, SO_2, Sn^{4+}$
D
$Fe^{3+}, SO_4^{2-}, S^{2-}, Sn^{4+}$

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Solution

$K_2Cr_2O_7$ in acidic medium acts as a strong oxidizing agent. It changes its colour from orange ( $Cr_2O_7^{2-}$ ) to green ( $Cr^{3+}$ ) when it reacts with a reducing agent.

We need to identify the set in which all species can act as reducing agents (i.e., they can be oxidized to a higher oxidation state).

In option (A), $Fe^{2+}$ oxidizes to $Fe^{3+}$ , $Sn^{2+}$ oxidizes to $Sn^{4+}$ , $I^-$ oxidizes to $I_2$ , and $S^{2-}$ oxidizes to $S$ . All of these are reducing agents.

In option (B), $Fe^{3+}$ is already in its maximum stable oxidation state and cannot be oxidized further.

In option (C), $Sn^{4+}$ cannot be oxidized further.

In option (D), $Fe^{3+}$ , $SO_4^{2-}$ , and $Sn^{4+}$ cannot be oxidized further.

Thus, only the species in option (A) will change the orange colour of $K_2Cr_2O_7$ .

Answer: $Fe^{2+}, Sn^{2+}, I^-, S^{2-}$

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JEE Main 2026 — Chemistry Inorganic Chemistry

2026mcqmedium

Which of the following sets includes all the species that will change the orange colour of $K_2Cr_2O_7$ in acidic medium?

Official previous-year question

Held on 2 Apr 2026 · Verified 6 Jul 2026.

Options

A
$Fe^{2+}, Sn^{2+}, I^-, S^{2-}$
B
$S^{2-}, Fe^{3+}, I^-, C_2O_4^{2-}$
C
$Fe^{2+}, NO_2^-, SO_2, Sn^{4+}$
D
$Fe^{3+}, SO_4^{2-}, S^{2-}, Sn^{4+}$

Did you get this right?

Solution

$K_2Cr_2O_7$ in acidic medium acts as a strong oxidizing agent. It changes its colour from orange ( $Cr_2O_7^{2-}$ ) to green ( $Cr^{3+}$ ) when it reacts with a reducing agent.

We need to identify the set in which all species can act as reducing agents (i.e., they can be oxidized to a higher oxidation state).

In option (A), $Fe^{2+}$ oxidizes to $Fe^{3+}$ , $Sn^{2+}$ oxidizes to $Sn^{4+}$ , $I^-$ oxidizes to $I_2$ , and $S^{2-}$ oxidizes to $S$ . All of these are reducing agents.

In option (B), $Fe^{3+}$ is already in its maximum stable oxidation state and cannot be oxidized further.

In option (C), $Sn^{4+}$ cannot be oxidized further.

In option (D), $Fe^{3+}$ , $SO_4^{2-}$ , and $Sn^{4+}$ cannot be oxidized further.

Thus, only the species in option (A) will change the orange colour of $K_2Cr_2O_7$ .

Answer: $Fe^{2+}, Sn^{2+}, I^-, S^{2-}$

Your note

JEE Main Inorganic Chemistry in other years

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JEE Main 2026 — Chemistry Inorganic Chemistry

Options

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Solution

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JEE Main Inorganic Chemistry in other years

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Physical Chemistry

Organic Chemistry

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JEE Main 2026 — Chemistry Inorganic Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Inorganic Chemistry in other years

More JEE Main Inorganic Chemistry questions

Other Chemistry topics for JEE Main

Physical Chemistry

Organic Chemistry

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