Chemistry S & P Block Elements MDCAT 2017
PMDC Verified Question 83 of 104
Following graph shows a physical property along the period 3 elements. Which physical property is this?

Si (Peak) Na Mg Al Si P S Cl Ar
A
Electron affinity
B
Non-metallic character
C
Atomic radius
D
Melting point up to group IVA
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Melting point up to group IVA
Concept:

Melting point across Period 3 elements increases from Na, Mg, Al to a peak at Si (Group IVA) due to its giant covalent macromolecular structure. After Si, it drops sharply for P, S, Cl, and Ar because they exist as simple molecular structures with weak intermolecular forces.

Solution:

  • The graph shows a clear peak at Si.
  • Among Period 3 physical properties, only Melting point reaches a peak at Group IVA (Si) and then decreases.


Why other options are incorrect:

  • Atomic radius: Consistently decreases from Na to Cl without any peak at Si.
  • Electron affinity & Non-metallic character: Generally increase across the period.

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