Chemistry S & P Block Elements NUMS 2022
PMDC Verified Question 60 of 104
Which of the following property increases down the group in alkali metals?
A
Ionization energy
B
Electron affinity
C
Reactivity
D
Electronegativity
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Reactivity
Concept:

For metals, chemical reactivity is dictated by how easily they can lose their valence electrons (their electropositive or metallic character).

Solution:

  • As you move down the alkali metal group (Group I-A, from Li to Cs), new electron shells are added, massively increasing the atomic radius.
  • This increased distance and greater shielding effect lower the Ionization Energy drastically.
  • Because it becomes progressively easier for the metal to lose its outermost electron, its chemical reactivity increases. (E.g., Li reacts slowly with water, while Cs reacts explosively).


Why other options are incorrect:

  • Options A, B, & D: Ionization energy, electron affinity (magnitude), and electronegativity all decrease down the group due to the increasing atomic size and shielding effect.

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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