Chemistry Solids ETEA 2023
PMDC Verified Question 23 of 54
Crystal having orthorhombic crystal system is:
A
\( \text{PbCrO}_4 \)
B
\( \text{BaSO}_4 \)
C
\( \text{ZnO} \)
D
\( \text{K}_2\text{Cr}_2\text{O}_2 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( \text{BaSO}_4 \)
Concept:
Different chemical compounds crystallize into specific lattice geometries based on their molecular symmetry and ionic sizes.

Solution:
  • The orthorhombic crystal system is defined by having three unequal axes (\( a \neq b \neq c \)) intersecting at 90-degree angles (\( \alpha = \beta = \gamma = 90^\circ \)).
  • Barium sulfate (\( \text{BaSO}_4 \)), commonly known as the mineral barite, is a classic textbook example that crystallizes in the orthorhombic system.


Why other options are incorrect:
  • C: Zinc oxide (\( \text{ZnO} \)) typically crystallizes in a hexagonal system (wurtzite structure).
  • A, D: These compounds belong to other crystalline systems (e.g., monoclinic/triclinic).

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