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11) Niobium (Nb) is a metal that crystalizes with cubic unit cell that is body-centered (BCC). Nb has an atomic radius of 143 pm. What is its density in g/cm3? A) 4.28 g/cm3 B) 17.1 g/cm3 r=143 C) 9.33 g/cm3 D) 52.8 g/cm3 E) 8.57 g/cm3

Answer 1

Density of a Cubic whit cell of a crystal is determined by the formula: da NX M a3XNA Where do density (g/cm3) no no. of atoms in an amit cell M2 Molecular weight. (almol) NĄ 2 Aox Avo grado's No. az elis internuclear distance between two atoms. (in cm). For Bec crystal structure radius 82 13a given radiuro = 143pm. -10 Molecular 2 330.24 pm. Atomic weight of Nb 2 92.9. 2 330 x 10 cm. . 2x 92.9 idz (330 X10-03 X 6.023x1023 Unit cell abomo no.is 2 . I for BCC > Foto

8.584 x 10-7 10-30 X1023 3 8.584x (0-30 - 10-30 density 2 8.584 g/cm3. 127 A mystery solution with a mole fraction of solute is 0.15. So the mole fraction of solrent isz (1-0.15 20.85 Now the total vapour pressure of the solution is a 65.0 forr. From the Roult's how we know Psowent 2 Xsolvent. Protal. - y total Pressure of mole fraction pressure. pure schert. in Powent 2 0.858 65 toor 255.25 torr.