UPSC Combined Geo-Scientist, Mains · 2020 · Mains Paper II
Q3. Formula units in rock-salt KCl
Question
KCl has rock-salt structure and density 1.98 g cm⁻³. Its first-order (200) reflection is at 6.5° for X-rays of wavelength 70.8 pm. Calculate formula units per unit cell.
Answer in brief
The calculation gives Z≈3.91≈4 KCl formula units per conventional cell.
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CoversFormula units in rock-salt KClCrystallography