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JEE Advanced Chemistry Electrochemistry 2024 JEE Advanced 2024 (Paper 1)

JEE Advanced Chemistry Question (2024) — Solution

Question

In a conductometric titration, small volume of titrant of higher concentration is added stepwise to a larger volume of titrate of much lower concentration, and the conductance is measured after each addition. The limiting ionic conductivity ( _0 ) values (in mS m ^2 ~mol ^ -1 ) for different ions in aqueous solutions are given below: For different combinations of titrates and titrants given in List-I, the graphs of 'conductance' versus 'volume of titrant' are given in List-II. Match each entry in List-I with the appropriate entry in List-II and choose the correct option.

Options

  1. A. P -4, Q -3, R -2, ~S -5
  2. B. P -2, Q -4, R -3, ~S -1
  3. C. P -3, Q -4, R -2, ~S -5
  4. D. P -4, Q -3, R -2, ~S -1

Answer

C. P -3, Q -4, R -2, ~S -5

Step-by-step solution

Option (P) : On adding AgNO _3 solution to KCl solution precipitation of AgCl will occur due to which Cl ^ - already present will be replaced by NO _3^ - ions. So conductance of solution will decrease till equivalence point. After complete precipitation of AgCl , further added AgNO _3 will increase the number of ions in resulting solution so conductance will increase. Option ( Q ) : On adding KCl solution to AgNO _3 solution precipitation of AgCl will occur due to which already present Ag ^ + ions will be replaced by K ^ + ions in solution. So conductance of solution will increase. After complete precipitation of AgCl further added KCl will increase the number of ions in resulting solution so conductance will increase further. Option (R) : On adding HCl solution to NaOH solution, OH ^ - will be replaced by Cl ^ - ions so conductance of solution decreases. After complete neutralisation further added HCl will increase number of ions in the solution. So conductance will increase further. Option (S) : On adding CH _3 COOH solution to NaOH solution OH ^ - will be replaced by CH _3 COO ^ - ions, so conductance of solution decreases. After complete neutralisation further added CH _3 COOH will remain undissociated because it is a weak acid and there is also common ion effect on acetate ions. So number of ions in solution will remain almost constant therefore conductance of solution will remain constant.

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