N=N/Na
----. N=nxNa=3x6.023x10^23=<span>1.8069e+24</span>
Explanation:
The given data is:
The mass% of a solution is 7.
Mass of solution =450g
The mass of salt required can be calculated as shown below:
Substitute the given values in this formula to get the mass of solute that is salt:
Mass of salt =31.5g
Mass of solvent that is water = 450g-31.5g=418.5g
Let's assume that H₂ gas has ideal gas behavior.
Then we can use ideal gas formula,
PV = nRT
Where,
P = Pressure of the gas (Pa)
V = Volume of the gas (m³)
n = moles of the gas (mol)
R = Universal gas constant (8.314 J K⁻¹ mol⁻¹)
T = Temperature in Kelvin (K)
But,
n = m/M,
Where m is mass of the gas (kg) and M is molar mass of the gas (kg/mol)
Hence PV= mTR / M
P = mTR / VM = (m/V)TR / M
m/V = d (density (kg/m³)
By rearranging,
P = dRT / M
d = 0.135 g/L = 0.135 kg/m³
T = (273 + 201) K = 474 K
M = 2 g/mol = 2 x 10⁻³ kg/mol
From substitution,
P = 0.135 kg/m³ x 8.314 J K⁻¹ mol⁻¹ x 474 K / 2 x 10⁻³ kg/mol
P = 266006.43 Pa
P = 266 kPa
Hence the pressure of H₂ gas at 201⁰C is 266 kPa
The best answer is A) <span>It shows how the temperature of the substance falls as heat is removed.
The cooling curve shows how the temperature of a substances changes with time, as it is allowed to cool. The substance is first heated until completely liquefied, and then allowed to cool. The flat parts of the curve, where temperature is constant with time, show the periods in which the state of matter of the substance changes. One the substance completely changes it state of matter, namely changes from liquid to solid, its temperature continues to drop.
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