Chemistry S & P Block Elements SZABMU 2024
PMDC Verified Question 11 of 104
Which of following sulphate of Group-II elements are insoluble?
A
\( \text{MgSO}_4 \)
B
\( \text{BeSO}_4 \)
C
\( \text{CaSO}_4 \)
D
\( \text{BaSO}_4 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( \text{BaSO}_4 \)
Concept:

The solubility of Group 2 sulphates decreases aggressively as you move down the group due to the rapid decline in hydration energy.

Solution:

  • The sulphate ion (\( \text{SO}_4^{2-} \)) is very large, so the lattice energy of these salts doesn't change much down the group.
  • However, as the metal cation gets larger (from Be to Ba), its ability to attract water molecules (hydration energy) drops dramatically.
  • Beryllium and Magnesium are small and have massive hydration energies, making \( \text{BeSO}_4 \) and \( \text{MgSO}_4 \) highly soluble in water.
  • Barium (Ba) is at the bottom of the group. Its large size yields a very low hydration energy that cannot overcome the lattice energy of the crystal.
  • Therefore, Barium sulphate (\( \text{BaSO}_4 \)) is highly insoluble (and is used in medicine as a "barium meal" precisely because it won't dissolve into the bloodstream).


Why other options are incorrect:

  • Be and Mg sulphates are soluble. Ca sulphate is sparingly soluble, but BaSO4 is the textbook definition of an insoluble Group II sulphate.

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