NEET Class neet Answered

Objective type of question

Asked by shahlaghazal009 | 24 Apr, 2019, 11:28: AM

Expert Answer

Question 37:

The density of argon (fcc) is 1.83 g/cm³ at 20 ^ºC. What is the length of an edge of a unit cell?

Given:

Density ρ = 1.83 g/cm³

Molar mass = 40

N_A = 6.022 × 10²³

We know,

straight rho space equals space fraction numerator nM over denominator straight N subscript straight A straight a cubed end fraction straight a cubed space equals space fraction numerator nM over denominator straight N subscript straight A straight rho end fraction space space space space space space equals fraction numerator 4 cross times 40 over denominator 6.022 cross times 10 to the power of 23 cross times 1.83 end fraction space space space space space space space equals space fraction numerator 160 over denominator 11.02 cross times 10 to the power of 23 end fraction space space space space space equals 14.51 cross times 10 to the power of negative 23 end exponent space space space space space space space straight a cubed space equals space 145.1 cross times 10 to the power of negative 24 end exponent space space straight a space space equals 5.25 space cross times 10 to the power of negative 8 end exponent space space space straight a space equals space 0.525 space cross times 10 to the power of negative 7 end exponent space cm space space space straight a space equals space 0.525 space nm space

Edge length is 0.525 nm.

Answered by Varsha | 25 Apr, 2019, 07:49: PM

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