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3 years ago

(a) The lattice constant of GaAs is 5.65 Å. Determine the number of Ga atoms andAs atoms per cm 3 .

Engineering

1 answer:

Natasha_Volkova [10]3 years ago

7 0

Answer:

a) Number of atoms per unit cell for Ga = 4 atoms per unit cell

Number of atoms per unit cell for As = 4 atoms per unit cell

b) Volume density of Germanium in its unit cell = 4.35 × 10²² /cm³

Explanation:

GaAs has a number density of 4.42 x 10²² atoms/cm³ from literature.

Since GaAs is known to contain almost equal amounts of Ga and As.

Number density of Ga = Number density of As = 2.21 × 10²² atoms/cm³

Number density = Number of atoms in a unit cell/volume of the unit cell

Number of atoms in the unit cell = ?

Volume of the unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³

Number of atoms per unit cell for Ga and As = number density × volume of unit cell = 2.21 × 10²² × 1.804 × 10⁻²² = 4 atoms/unit cell

b) Volume density = Number of atoms per unit cell/volume of unit cell

Germanium has 8 atoms per unit cell (from literature),

Volume of unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³

Volume density = 8/(1.804 × 10⁻²²) = 4.35 × 10²² /cm³

Hope this helps!

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Answer:

0.5°c

Explanation:

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Humidity ratio expressed by mass:

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where

x = humidity ratio (kgwater/kgdry_air, lbwater/lbdry_air)

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ma = mass of dry air (kg, lb)

It can be as:

x = 0.005 (100) / [(100 - 100)]

x = 0.005 x 100 / (100 - 100)

x = 0.005 x 100 / 0

x = 0.5°c

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3 years ago

Twenty-five wooden beams were ordered or a construction project. The sample mean and he sample standard deviation were measured

aksik [14]

Answer:

Correct option: B. 90%

Explanation:

The confidence interval is given by:

$CI = [\bar{x} - z\sigma_{\bar{x}} , \bar{x}+z\sigma_{\bar{x}} ]$

If $\bar{x}$ is 190, we can find the value of $z\sigma_{\bar{x}}$ :

$\bar{x} - z\sigma_{\bar{x}} = 188.29$

$190 - z\sigma_{\bar{x}} = 188.29$

$z\sigma_{\bar{x}} = 1.71$

Now we need to find the value of $\sigma_{\bar{x}}$ :

$\sigma_{\bar{x}} = s / \sqrt{n}$

$\sigma_{\bar{x}} = 5/ \sqrt{25}$

$\sigma_{\bar{x}} = 1$

So the value of z is 1.71.

Looking at the z-table, the z value that gives a z-score of 1.71 is 0.0436

This value will occur in both sides of the normal curve, so the confidence level is:

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The nearest CI in the options is 90%, so the correct option is B.

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4 years ago

A rigid tank whose volume is 2 m3, initially containing air at 1 bar, 295 K, is connected by a valve to a large vessel holding a

bazaltina [42]

Answer:

$Q_{cv}=-339.347kJ$

Explanation:

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$m_1=232kg$

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$8bar*|\frac{100kPa}{1bar}|*2=m_2*0.287*350$

$m_2=11.946$

So, the total mass of the aire entered is

$m_v=m_2-m_1\\m_v=11.946-2.362\\m_v=9.584kg$

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At the end we make a Energy balance, so

$U_{cv}(t)-U_{cv}(t)=Q_{cv}-W{cv}+\sum_i m_ih_i - \sum_e m_eh_e$

No work done there is here, so clearing the equation for Q

$Q_{cv} = m_2u_2-m_1u_1-h_1(m_v)$

$Q_{cv} = (11.946*250.02)-(2.362*210.49)-(295.17*9.584)$

$Q_{cv}=-339.347kJ$

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3 years ago

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Answer:

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Explanation:

NB: kindly check below for the attached picture.

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notka56 [123]

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