IIT-JEE 2011 · Paper 1 · Chemistry Q5

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ChemistrySingle correct+3 / -1Question 5 of 69

$\ce{AgNO3}$ (aq.) was added to an aqueous KCl solution gradually and the conductivity of the solution was measured. The plot of conductance ( $\Lambda$ ) versus the volume of $\ce{AgNO3}$ is

Four plots of conductance Λ against volume of AgNO₃, each with the equivalence point marked by a dashed line. (P) falls steeply, then rises. (Q) dips slightly, rises slowly, then rises steeply. (R) rises slightly, then falls slightly. (S) stays flat, then rises steeply.

(P)

(Q)

(R)

(S)

Answer and worked solution

Official answer: D

Before the end point $\ce{Ag+ + Cl- -> AgCl v}$ : each Cl⁻ removed is replaced by an NO₃⁻ of similar mobility, so the conductance stays almost constant.

After it excess Ag⁺ and NO₃⁻ accumulate and the conductance rises: graph (S).

(D)

Topics:Conductance and Kohlrausch's law Anion analysis

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IIT-JEE 2011 · Paper 1, Chemistry question 5