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The Solid State

Question
CBSEENCH12011045
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Lithium has a bcc structure. Its density is 530 kg m-3 and its atomic mass is 6.94 g mol-1. Calculate the edge length of a unit cell of lithium metal. (NA = 6.02 x 1023 mol-1).

  • 352pm

  • 527pm

  • 264pm

  • 154pm

Solution

A.

352pm

Given, Li has a bcc structure
Density (ρ) =530 kg-m-3
atomic mass (M) = 6.94 g mol-1
Avogadro's number of atoms per unit cell in bcc (Z) = 2.
∴ we have the formula for density.
straight rho space equals space fraction numerator straight z space straight x space straight M over denominator straight N subscript straight A space straight x space straight a cubed end fraction where space straight a space equals space edge space length space of space straight a space unit space cell straight a space equals space 3 square root of fraction numerator straight Z space xM over denominator straight rho space straight x space straight N subscript straight A end fraction end root straight a space equals space 3 square root of fraction numerator 2 space straight x 6.94 space straight g space mol to the power of negative 1 end exponent over denominator 0.53 space straight g space straight x space 6.02 space straight x space 10 to the power of 23 space mol to the power of negative 1 end exponent end fraction end root straight a space equals space space 3 square root of 4.35 space straight x space 10 to the power of negative 23 end exponent space cm to the power of negative 3 end exponent end root space equals space 3.52 space straight x space 10 to the power of negative 8 end exponent straight a space equals space 3.52 space pm

Some More Questions From The Solid State Chapter

Classify the following solids in different categories based on the nature of intermolecular forces operating in them:
Potassium sulphate, tin, benzene, urea, ammonia, water, zinc
sulphate, graphite, rubidium, argon, silicon carbide.

Solid A is a very hard, electrical insulator in solid as well as in molten state and melts at extremely high temperature. What type of solid is it?

Ionic solids conduct electricity in liquid state but not in solid state. Explain.

What type of solids are electrical conductors, malleable and ductile?

Give the significance of a 'lattice point'.

Name the parameters that characterize a unit cell.

Distinguish between Hexagonal and monoclinic unit cells.

Distinguish between Face-centred and end-centred unit cells.

What is the two-dimensional coordination number of a molecule in square close packed layer ?

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