AIIMS Chemistry Redox Reactions Class 11 Questions

Assertion: $\text{S}_2\text{O}_7^{2-}$ & $\text{Cr}_2\text{O}_7^{2-}$ both exist. Reason: Both have same valence electrons.

Which of the following can react with K₂Cr₂O₇

The chemical reaction of Zn with conc. HNO₃, 4Zn+10HNO₃ (dil.) → 4Zn(NO₃)₂ + 5H₂O⁺N₂O Zn reacts differently with very dilute HNO₃ Reaction with Zn with conc. HNO₃ + 2NO₂

The chemical reaction is shown below:

The element that can have oxidation state from 4 to 6 is chromium, Cr. Its oxidation state varies from +1 to +6.

In redox reactions potassium dichromate is used as an oxidizing agent. 2CrO₄²⁻ + H⁺ → Cr₂O₇²⁻ + H₂O. Potassium dichromate is orange in color and used in redox titrations. But it is not stable in both acid and base. So, option (3) is incorrect.

In order to oxidise a mixture of one mole of each of FeC₂O₄, Fe₂(C₂O₄)₃, FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is:

The melting point of CrO₃ and Al₂O₃ are 197 °C and 2072 °C respectively. CrO₃ x - 6 = 0 x = 6 Al₂O₃ 2x - 6 = 0 x = 3 Therefore, both statements are correct but Reason is not the correct explanation of Assertion

Which of the following can react with $\text{K}_2\text{Cr}_2\text{O}_7$

Consider the molecular structure of CrO₅ is, The oxidation number is calculated as, x + (-2) + 4(-1) = 0, x = 6. Thus, the oxidation number of CrO₅ atom cannot be higher than valence electrons.

When the Iodine reacts with sulphur dioxide, the reaction will be: I₂ + SO₂ + Starch (deep blue) → I⁻ + SO₄²⁻. The solution is colorless solution.

For the reaction, $$\text{Cr}_2\text{O}_7^{2-} \xrightarrow{\text{pH}=x} \text{CrO}_4^{2-} \xrightarrow{\text{pH}=y} \text{Cr}_2\text{O}_7^{2-}$$

The mass of potassium dichromate crystals required to oxidise 3 750 $cm^{3}$ of 0.6 M Mohr's salt solution is (Given, molar mass, potassium dichromate = 294, Mohr's salt = 392)

Best reagent for the conversion of AgNO₃ to Ag is

Chlorine oxidizes sodium thiosulphate to form

Substances that are oxidized and reduced in the following reaction are respectively. N₂H₄(l) + 2H₂O₂(l) → N₂(g) + 4H₂O(l)

Which of the following can be oxidized by SO₂?

In electrorefining of copper some gold is deposited at

K₂Cr₂O₇ in acidic medium converts into

MnO₃ in an acidic medium dissociates into

Predict the product of reaction of I₂ with H₂O₂ in basic medium.

When KMnO₄ reacts with KBr in alkaline medium gives bromate ion. Then oxidation state of Mn changes from +7 to

Assertion : Sulphur is oxidised by H₂O₂ in presence of Fe (III). Reason : Fe (III) oxidises sulphur to sulphate.

Assertion : Chlorine undergoes disproportionation reaction in alkaline medium.

Assertion: The formal oxidation no. of sulphur in Na2S4O6 is 2.5.

Bromine is added to cold dilute aqueous solution of NaOH. The mixture is boiled. Which of the following statements is not true?

To a 25 ml H₂O₂ solution, excess of acidified solution of KI was added. The iodine liberated required 20 ml of 0.3 N Na₂S₂O₃ solution. The volume strength of H₂O₂ solution is

The correct order of stability of the superoxides is

Assertion : The S⁻S⁻S bond angle in S₈ molecule is 105°. Reason : S₈ has a V⁻shape.

Which two of the following salts are used for preparing iodized salt? (i) KIO₃, (ii) KI, (iii) I₂, (iv) HI

In the balanced chemical reaction IO₃⁻ + aI⁻ + bH⁺ → cI₂ + dH₂O a, b, c and d respectively corresponds to

Assertion : Reaction of SO₂ and H₂S in the presence of Fe₂O₃ catalyst gives elemental sulphur. Reason : SO₂ is a reducing agent.

Assertion : Ozone is a powerful oxidising agent in comparison to O₂. Reason : Ozone is diamagnetic but O₂ is paramagnetic.

For decolourization of 1 mole of KMnO₄, the moles of H₂C₂O₄ required is

Assertion : HClO₄ is a stronger acid than HClO₃. Reason : Oxidation state of Cl in HClO₄ is +8 and in HClO₃, +5.

MnO₂ (± 1 mole) in neutral aqueous medium is disproportionated to

Assertion : PbI₄ is a stable compound. Reason : Iodide stabilizes higher oxidation state.

Oxidation state of Fe in Fe₃O₄ is

Assertion : Stannous chloride gives grey precipitate with mercuric chloride, but stannic chloride does not do so. Reason : Stannous chloride is a powerful oxidising agent which oxidises mercuric chloride to metallic mercury.

Assertion (A) : In some cases oxygen shows positive oxidation number though it is an electronegative element. Reason (R) : Fluorine is more electronegative than oxygen.

Oxidation state of sulphur in S₈, H₂S and SF₂ is

Assertion: Formic acid reduces mercuric chloride to mercurous chloride on heating, while acetic acid does not. Reason: Formic acid is stronger than acetic acid.