Answer:
The number of periods shows you the number of _______
<u>Electron Shell</u>
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Explanation:
<u><em>Modern periodic table is divided into Groups and Periods.</em></u>
A period is the horizontal row of the periodic table. There are <u>seven periods </u>in the periodic table.
It describes the following :
- The period in which a particular element found will show its <u>electron shell</u>
- The first period has Hydrogen and Helium = 1 - shell
- The second Period has Lithium to neon = 2- shells
A group is the vertical column of the periodic table . There are <u>18 groups</u> in total.
It describes the following :
The group number of the element is same as the<u> number of electrons in the outermost shell.</u>
The element having group 1 has = 1 electron in outer shell (example Na, K)
The element having group 2 has = 2 electron in outer shell (example Ca, Mg)
The element having group 0 has = full outer shell (example Ne Xe). these are also known as noble gases
Explanation:
In an ionic compound, there will be strong force of attraction between the combining atoms due to the opposite charges present on them.
For example, 
is an ionic compound where calcium has a +2 charge and each bromine atom has a -1 charge.
Therefore, in order to break the bond we need to provide more heat. Hence, boiling point of calcium bromide will be the highest.
is a covalent compound and as nitrogen is more electronegative in nature and also has a lone pair of electron hence, there will be a net dipole moment.
is also a covalent compound. And, as bromine is more electronegative than carbon atom so, dipole moment is in the outwards direction. Hence, in there will be zero dipole moment.
Therefore, its boiling is less than the boiling point of .
is a covalent compound and there will be no dipole moment.
Thus, we can conclude that given bromine-containing compounds are placed in their increasing boiling point order as follows.
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Acetic acid is the closest to 4.5 in my opinion.
Answer:
X(EtOH) = 0.0891
X(H₂O) = 0.9109
Explanation:
Given 20% aqueous solution ethanol.
Ethanol => C₂H₅OH (or, EtOH) => molecular weight = 46 g//mole
20% solution by weight = 20 grams EtOH / 100 grams of solution
20 grams EtOH / 100 grams of solution = 20 grams EtOH + 80 grams H₂O
moles EtOH = (20g/46g/mol) = 0.4348 mole
moles H₂O = (80g/18g/mol) = 4.4444 mole
moles EtOH + moles H₂O = 0.4348 + 4.4444 = 4.8792
X(EtOH) = 0.4348/4.8792 = 0.0891
X(H₂O) = 4.4444/4.8792 = 0.9109
∑mole fractions must equal 1.000 => 0.0891 + 0.9109 = 1.000 (check!)
