Chemistry Electrochemistry NUMS 2019
PMDC Verified Question 49 of 73
Which of the following metal does not liberate hydrogen on reaction with acid?
A
Mg
B
Pt
C
Zn
D
Ca
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Pt
Concept:

Metals located above Hydrogen in the electrochemical series (negative reduction potentials) are reactive enough to displace \( H^+ \) ions from dilute acids, generating \( H_2 \) gas.

Solution:

  • Platinum (Pt) is a highly unreactive, noble metal situated far below Hydrogen in the electrochemical series.


  • It has a high positive reduction potential (\( +1.20 \text{ V} \)).


  • Because its oxidation potential is negative relative to Hydrogen, it cannot spontaneously reduce \( H^+ \) ions into \( H_2 \) gas.


Why other options are incorrect:

Magnesium, Zinc, and Calcium all have negative reduction potentials (they lie above Hydrogen) and act as strong reducing agents, eagerly dissolving in acids to liberate hydrogen gas.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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