Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE MainChemistryRedox Reactions

Match List I with List II. List I (Reagent) List II (Reason it is not a primary standard) A. NaOH I. Deliquescent nature B. KMnO ₄ II. Photochemical decomposition and traces of MnO ₂ C. FeSO ₄ 7 H ₂ O III. Susceptible to aerial oxidation D. Na ₂ Cr ₂ O ₇ IV. Highly hygroscopic and absorbs CO ₂ Choose the correct answer from the options given below:

Options

  1. AA-I, B-III, C-II, D-IV
  2. BA-IV, B-II, C-III, D-I
  3. CA-IV, B-III, C-II, D-I
  4. DA-IV, B-II, C-I, D-III

Correct answer

B. A-IV, B-II, C-III, D-I

Step-by-step solution

A primary standard must be highly pure, stable, and non-hygroscopic. NaOH is highly hygroscopic and readily absorbs CO ₂ from the atmosphere to form sodium carbonate, so it cannot be used as a primary standard (A IV). KMnO ₄ is not perfectly pure as it usually contains traces of MnO ₂ , and its aqueous solution is unstable towards light (photochemical decomposition) (B II). FeSO ₄ 7 H ₂ O is unstable because the Fe ²⁺ ions are easily oxidized to Fe ³⁺ by atmospheric oxygen (C III). Na ₂ Cr ₂ O ₇ is highly deliquesc

Practice Redox Reactions on Quantrex Academy →

More from Redox Reactions

500 mL of 0.2 M MnO₄^- solution in basic medium when mixed with 500 mL of 1.5 M KI solution, oxidises iodide ions to liberate molecular iodine. This liberated iodine is then titrat 2026Given below are two statements: Statement I: Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis. Statement II: Phenolphthalein i 2026In order to oxidise a mixture of 1 mole each of FeC₂O₄ , Fe₂(C₂O₄)₃ , FeSO₄ and Fe₂(SO₄)₃ in acidic medium, the number of moles of KMnO₄ required is 2026500 mL of 1.2 M KI solution is mixed with 500 mL of 0.2 M KMnO ₄ solution in basic medium. The liberated iodine was titrated with standard 0.1 M Na ₂ ~S ₂ O ₃ solution in the prese 2026One mole of Cl ₂( ~g ) was passed into 2 L of cold 2 M KOH solution. After the reaction, the concentrations of Cl ⁻, ClO ⁻ and OH ⁻ are respectively (assume volume remains constant 2026X and Y are the number of electrons involved, respectively during the oxidation of I ⁻ to I ₂ and S ²⁻ to S by acidified K ₂ Cr ₂ O ₇ . The value of X + Y is _ _ _ _ . 2026200 cc of x 10⁻³ M potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here x= _ _ _ _ . 2026Identify the correct statements : A. Hydrated salts can be used as primary standard. B. Primary standard should not undergo any reaction with air. C. Reactions of primary standard 2026 Full Redox Reactions list All JEE Main PYQs