Chemistry S & P Block Elements SET 2019
PMDC Verified Question 70 of 104
Which one of the following properties decreases across the third period of elements in the periodic table?
A
Electronegatively
B
Ability to act as reducing agent
C
Ionization energy
D
Melting and boiling points
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Ability to act as reducing agent
Concept:

A reducing agent is a substance that donates electrons easily (gets oxidized). The ability to act as a reducing agent is directly related to metallic character and low Ionization Energy.

Solution:

  • As we move left to right across the 3rd period (from Na to Ar), the effective nuclear charge increases, and atomic size decreases.
  • This makes it increasingly difficult for atoms to lose their valence electrons (Ionization Energy increases).
  • Because they become less willing to donate electrons, their ability to act as a reducing agent consistently decreases. (In fact, they transition into strong oxidizing agents, like Chlorine).


Why other options are incorrect:

  • Option A & C: Electronegativity and Ionization Energy consistently increase across the period.
  • Option D: Melting/boiling points increase up to Group IVA, then decrease, so it is not a consistent decrease across the entire period.

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.

Previous Question All S & P Block Elements MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App