However, as a result of the Sun's large angular size, solar<span> illumination is only partially blocked in the outer portion of the Earth's </span>shadow<span>, which is given the name penumbra. A penumbral </span>eclipse<span> occurs when the Moon passes through the Earth's penumbra. The penumbra causes a subtle darkening of the Moon's surface.</span>
Answer:

Explanation:
Hello,
In this case, by-mass percent is computed in terms of the mass of the solute and the mass of the solvent as shown below:

Thus, solving for the mass of the solution, we obtain:

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The question is incomplete, here is the complete question:
Calculate the mole fraction of the ionic species KCl in the solution A solution was prepared by dissolving 43.0 g of KCl in 225 g of water.
<u>Answer:</u> The mole fraction of KCl in the solution is 0.044
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
Given mass of water = 225 g
Molar mass of water = 18 g/mol
Putting values in equation 1, we get:

Given mass of KCl = 43 g
Molar mass of KCl = 74.55 g/mol
Putting values in equation 1, we get:

Mole fraction of a substance is given by:

Moles of KCl = 0.577 moles
Total moles = [0.577 + 12.5] = 13.077 moles
Putting values in above equation, we get:

Hence, the mole fraction of KCl in the solution is 0.044
Answer:
The answer to your question is below:
Explanation:
Having exactly the same data as the previous experiment I think that having the same data as the previous experiment is extremely important but not the most important, for me is the second most important.
Using the same procedure and variables as the previous experiment For me, this is the most importan thing when a scientist is designing an experiment, because if he or she follow exactly the same procedure and variables, then the results will be very close.
Conducting an experiment similar to the previous experiment This characteristic is important but not the most important.
Using the same laboratory that was used in the previous experiment It is not important the laboratory, if the procedure and variables are the same, your experiment must give the same results in whatever laboratory.