NEET Chemistry The Solid State Questions Solved

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An element with density 2.8 g cm-3 forms a f.c.c. unit cell with edge length 4×10-8 cm. Calculate the molar mass of the element.

(Given : NA = 6.022×1023 mol-1)

Using formula : ρ = Z×Ma3×N0 for f.c.c, Z = 4

M = ρ×a3×N0Z

 M = (2.8g cm-3)(4×10-8cm)3(6.022×1023atoms mol-1)4

 Molar mass, M = 1079.142440 = 26.978 g/mol

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