SATHEE: Solid State - Result Question 7

Solid State - Result Question 7

####7. A solid having density of $9 \times 10^{3} k g m^{- 3}$ forms face centred cubic crystals of edge length $200 \sqrt{2} p m$ . What is the molar mass of the solid?

[Avogadro constant $= 6 \times 10^{23} m o l^{- 1}, π = 3]$

(2019 Main, 11 Jan I)

(a) $0.03050 k g m o l^{- 1}$

(b) $0.4320 k g m o l^{- 1}$

(d) $0.0216 k g m o l^{- 1}$

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Answer:

Correct Answer: 7. (a)

Solution:

Density of a crystal

$d = \frac{M \times Z}{N_{A} \times a^{3}} \Rightarrow M = \frac{d \times N_{A} \times a^{3}}{Z}$

Given, $d = 9 \times 10^{3} k g m^{- 3}$

$\begin{aligned} M & = Molar mass of the solid \\ Z & = 4 (for fcc crystal) \\ N_{A} & = Avogadro’s constant = 6 \times 10^{23} m o l^{- 1} \\ a & = Edge length of the unit cell \\ = 200 \sqrt{2} p m = 200 \sqrt{2} \times 10^{- 12} m \end{aligned}$

On substituting all the given values, we get

$\begin{aligned} = \frac{(9 \times 10^{3}) k g m^{- 3} \times (6 \times 10^{23}) m o l^{- 1} \times {(200 \sqrt{2} \times 10^{- 12})}^{3} m^{3}}{4} \\ = 0.0305 k g m o l^{- 1} \end{aligned}$

Solid State - Result Question 7

Answer:

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Solid State - Result Question 7

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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