JEE Main 2017 · 8 Apr · Shift 1 · Chemistry Q47

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ChemistrySingle correct+4 / -1Question 47 of 90

Consider the following standard electrode potentials (E° in volts) in aqueous solution :

Element	$\ce{M^3+/M}$	$\ce{M+/M}$
Al	−1.66	+0.55
Tl	+1.26	−0.34

Based on these data, which of the following statements is correct ?

\ce{Tl+}

is more stable than

\ce{Al^3+}

\ce{Al+}

is more stable than

\ce{Al^3+}

\ce{Tl+}

is more stable than

\ce{Al+}

\ce{Tl^3+}

is more stable than

\ce{Al^3+}

Answer and worked solution

Official answer: C

$E^\circ(\ce{Tl+/Tl})=-0.34$ V is negative, so $\ce{Tl+}$ is stable, whereas $E^\circ(\ce{Al+/Al})=+0.55$ V shows $\ce{Al+}$ is not. So $\ce{Tl+}$ is more stable than $\ce{Al+}$ (the inert-pair effect).

Topics:Group 13 Galvanic cells and EMF

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JEE Main 2017 · 8 Apr · Shift 1, Chemistry question 47