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3 years ago

15

. Anthony proposed an experiment during which he would test the friction created when a skateboard is rolled along a flat surfac

e. He selected three different surfaces (carpet, tile, and concrete) each with three different textures (dry, wet, and icy). His teacher told him that he would need to clarify his experiment before his project would be approved. Which of the following best describes why Anthony's project was rejected? A. Anthony's project has two independent variables. B. Anthony does not have a problem that can be tested. C. The skateboard will not be able to roll along the carpet. D. The friction created by a skateboard cannot be measured.

1 answer:

lyudmila [28]3 years ago

8 0

Answer:D

Explanation:I think

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Why do we experience the changing of the seasons on earth

iren2701 [21]

<u>Answer:</u>

Earth's axis and position around the sun.

<u>Explanation:</u>

Earth's tilted axis causes the seasons to change. Throughout the year, different parts of Earth acquire the Sun's most direct rays(Or heat) because of the orbital rotation of Earth. So, when the North Pole tilts toward the Sun, it's summer inside the Northern Hemisphere. And whilst the South Pole tilts towards the Sun, it is winter within the Northern Hemisphere and vise versa.

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Calculate the solubility of hydrogen in water at an atmospheric pressure of 0.380 atm (a typical value at high altitude).

Pani-rosa [81]

The question is incomplete, here is the complete question:

Calculate the solubility of hydrogen in water at an atmospheric pressure of 0.380 atm (a typical value at high altitude).

Atmospheric Gas Mole Fraction kH mol/(L*atm)

$N_2$ $7.81\times 10^{-1}$ $6.70\times 10^{-4}$

$O_2$ $2.10\times 10^{-1}$ $1.30\times 10^{-3}$

Ar $9.34\times 10^{-3}$ $1.40\times 10^{-3}$

$CO_2$ $3.33\times 10^{-4}$ $3.50\times 10^{-2}$

$CH_4$ $2.00\times 10^{-6}$ $1.40\times 10^{-3}$

$H_2$ $5.00\times 10^{-7}$ $7.80\times 10^{-4}$

<u>Answer:</u> The solubility of hydrogen gas in water at given atmospheric pressure is $1.48\times 10^{-10}M$

<u>Explanation:</u>

To calculate the partial pressure of hydrogen gas, we use the equation given by Raoult's law, which is:

$p_{\text{hydrogen gas}}=p_T\times \chi_{\text{hydrogen gas}}$

where,

$p_A$ = partial pressure of hydrogen gas = ?

$p_T$ = total pressure = 0.380 atm

$\chi_A$ = mole fraction of hydrogen gas = $5.00\times 10^{-7}$

Putting values in above equation, we get:

$p_{\text{hydrogen gas}}=0.380\times 5.00\times 10^{-7}\\\\p_{\text{hydrogen gas}}=1.9\times 10^{-7}atm$

To calculate the molar solubility, we use the equation given by Henry's law, which is:

$C_{H_2}=K_H\times p_{H_2}$

where,

$K_H$ = Henry's constant = $7.80\times 10^{-4}mol/L.atm$

$p_{H_2}$ = partial pressure of hydrogen gas = $1.9\times 10^{-7}atm$

Putting values in above equation, we get:

$C_{H_2}=7.80\times 10^{-4}mol/L.atm\times 1.9\times 10^{-7}atm\\\\C_{CO_2}=1.48\times 10^{-10}M$

Hence, the solubility of hydrogen gas in water at given atmospheric pressure is $1.48\times 10^{-10}M$

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