Answer:

Explanation:
Hello,
In this case, for such formation of sulfur hexafluoride, the standard enthalpy of formation is -1220.47 kJ/mol (data extracted from NIST database). Next, we compute the moles in 10.0 grams of sulfur hexafluoride as shown below:

Next, for the given energy, we compute the total heat that is liberated:

Finally, we conclude such symbol has sense since negative heat is related with liberated heat.
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Answer:
Ok, so the process here is to convert the mass of H2 (hydrogen gas) to moles by dividing the mass by the molar mass of H2. Once you have the moles then you have to multiply by the STP (standard temperature and pressure) molar volume which should be 22.4.
Molar mass of H2 = (1.01)x2 = 2.02g/mol
19.3/2.02 = 9.55 moles
Now just multiply the moles by the molar volume
9.55 moles x 22.4 = 213.92 Litres of H2 are in 19.3g of H2
I think it’s c but I could be wrong
The Density of the metal is 5.6 g/cm³
<h3>What is the density of a substance?</h3>
The density of a substance is the ratio of the mass and the volume of the substance.
The density of the metal is calculated as follows:
mass of metal = 1.4 kg = 1400 g
volume of metal = 3.2 * 17.1 * 4.6 = 251.712 cm³
Density of metal = 1400 g/251.712 cm³
Density of the metal = 5.6 g/cm³
Therefore, the density of the metal is obtained from the mass and the volume of the metal.
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In the periodic table the lanthanoid and the actinides are place separately at the bottom because of their electronic configuration and their properties compared to the other elements.
The the lanthanoid and the actinides are place separately at the bottom in the periodic table due to their electronic configuration and the properties. and to make the periodic table more convenient . if we place the f block elements that is he lanthanoid and the actinides then the size of the periodic table will increase. the f block elements are called as the inner transition element.
Thus , to make the periodic table more convenient and to group the elements in the block the the lanthanoid and the actinides are place separately at the bottom.
To learn more about lanthanoid and actinide here
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