Question

The standard electrode potential $(\frac{M^{3+}}{M^{2+}})$ for V, Cr, Mn & Co are –0.26 V, –0.41 V, +1.57 V and +1.97 V, respectively. The metal ions which can liberate H2 from a dilute acid are

• A. V2+ and Cr2+
• B. V2+ and Mn2+
• C. Cr2+ and Co2+
• D. Mn2+ and Co2+

Answer 1

Answer: (A)

V2+ and Cr2+

Answer 2

E° of H+ /H2 is zero
So, The metals having less reduction potential can produce H2 gas with dilute acid.
Therefore V and Cr metal can produce H2 gas