AP EAMCET202124 Aug 2021Morning ShiftChemistrySolid StateActual
How many unit cells are present in a cube shaped ideal crystal of NaCl of mass lg?
Options
- A5.14 10²¹
- B1.28 10²⁴
- C1.71 10²¹
- D2.5 10²¹
Correct answer
D. 2.5 10²¹
Step-by-step solution
Molar mass of NaCl =58.5 lg of NaCl = 1 58.5 mole of NaCl 1 ~g of NaCl = 1 58.5 6.022 10²³ molecules of NaCl 4 molecules of NaCl are present as Cl ⁻ present occupy fcc lattice =4 ions of Cl ⁻ occupy Na ⁺ octahedral site =4 ions of Na ⁺ 1 unit cell contain 4 molecules of NaCl 1 molecule contain 1 4 unit cell. 1 58.5 6.022 10²³ molecule contains = 1 58.5 6.022 10²³ 4 unit cell Thus, 1 ~g of NaCl contain =2.57 10²¹ unit cell.