<u><em>NOTES TO TAKE DOWN: </em></u>
<em>Apparent brightness is a human measurement, and it would change for each star if the measurement were taken from another location. The more precise counterpart of apparent brightness is called absolute brightness (or absolute magnitude) and is the measure of the luminosity of a star, but on a common scale.</em>
<u><em>ANSWER:</em></u>
<em>Absolute brightness is the actual amount of light produced by the star, whereas apparent brightness changes with distance from the observer.</em>
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Answer:
Mass = 182.4 g
Explanation:
Given data:
Number of moles of Al₂O₃ = 3.80 mol
Mass of oxygen required = ?
Solution:
Chemical equation:
4Al + 3O₂ → 2Al₂O₃
Now we will compare the moles of aluminum oxide and oxygen.
Al₂O₃ : O₂
2 : 3
3.80 : 3/2×3.80 = 5.7
Mass of oxygen:
Mass = number of moles × molar mass
Mass = 5.7 mol × 32 g/mol
Mass = 182.4 g
halogens
Group 7A (or VIIA) of the periodic table are the halogens: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
Answer: 4.0 g/mL
Explanation:
The volume increased by 5.0 mL. Recall that the number of significant figures is equal to the number of certain values you can read plus one. Here, the volume increased from 14.0 mL to 19.0 mL, so the volume of X is 5.0 mL.