A diatomic molecule X2 has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is 6.17 g cm⁻³. The number of molecules present in 200 g of X2 is (Avogadro constant (N_A) = 6 × 10²³ mol⁻¹)

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Accepted Answer

4 N_A. For bcc, Z = 2 molecules/cell. Cell volume = (300 pm)^3 = (3e-8 cm)^3 = 2.7e-23 cm^3. Mass of cell = density x volume = 6.17 x 2.7e-23 = 1.666e-22 g, so molar mass M = (1.666e-22/2) x N_A = (8.33e-23)(6e23) = 50 g/mol. Then 200 g = 200/50 = 4 mol = 4 N_A molecules.

A diatomic molecule X2 has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is 6.17 g cm⁻³. The number of molecules present in 200 g of X2 is (Avogadro constant (N_A) = 6 × 10²³ mol⁻¹)

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