Answer:
A
Explanation:
The law of included fragments states: Fragments found in a rock must be older than the rock itself.
Answer:
This means a sample of 73.2 grams As atoms weighs less than the same amount of Kr atoms
Explanation:
Step 1: Data given
Mass of As = 73.2 grams
Molar mass As = 74.92 g/mol
Molar mass of Kr = 83.80 g/mol
Step 2: Calculate moles As
Moles As = Mass As / molar mass As
Moles As = 73.2 grams . 74.92 g/mol
Moles As = 0.977 moles
Step 3: Calculate As atoms
As atoms = moles As * number of Avogadro
As atoms = 0.977 moles * 6.02 * 10^23
As atoms = 5.88 *10^23 As atoms
Step 4: Calculate moles Kr
Moles Kr = Atoms Kr / number of Avogadro
Moles Kr = 5.88 * 10^23 Kr atoms / 6.02 *10^23
Moles Kr = 0.977 moles
Step 5: Calculate mass Kr
Mass Kr = moles Kr * molar mass Kr
Mass Kr = 0.977 moles * 83.80 g/mol
Mass Kr = 81.9 grams
This means a sample of 73.2 grams As atoms weighs less than the same amount of Kr atoms
Answer:
The Yerkes-Dodson Law suggests that there is a relationship between performance and arousal. Increased arousal can help improve performance, but only up to a certain point.
Explanation:
The pressure of the gas in the flask (in atm) when Δh = 5.89 cm is 1.04 atm
<h3>Data obtained from the question</h3>
The following data were obtained from the question:
- Atmospheric pressure (Pa) = 730.1 torr = 730.1 mmHg
- Change in height (Δh) = 5.89 cm
- Pressure due to Δh (PΔh) = 5.89 cmHg = 5.89 × 10 = 58.9 mmHg
- Pressure of gas (P) =?
<h3>How to determine the pressure of the gas</h3>
The pressure of the gas can be obtained as illustrated below:
P = Pa + PΔh
P = 730.1 + 58.9
P = 789 mmHg
Divide by 760 to express in atm
P = 789 / 760
P = 1.04 atm
Thus, the pressure of the gas when Δh = 5.89 cm is 1.04 atm
Learn more about pressure:
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Missing part of question:
See attached photo
To know this you pretty much do have to kind of memorize a few electronegativities. I don't recall ever getting a table of electronegativities on an exam.
From the structure, you have:
I remember the following electronegativities most because they are fairly patterned:
EN
H
=
2.1
EN
C
=
2.5
EN
N
=
3.0
EN
O
=
3.5
EN
F
=
4.0
EN
Cl
=
3.5
Notice how carbon through fluorine go in increments of
~
0.5
. I believe Pauling made it that way when he determined electronegativities in the '30s.
Δ
EN
C
−
Cl
=
1.0
Δ
EN
C
−
H
=
0.4
Δ
EN
C
−
C
=
0.0
Δ
EN
C
−
O
=
1.0
Δ
EN
O
−
H
=
1.4
So naturally, with the greatest electronegativity difference of
4.0
−
2.5
=
1.5
, the
C
−
F
bond is most polar, i.e. that bond's electron distribution is the most drawn towards the more electronegative compound as compared to the rest.
When the electron distribution is polarized and drawn towards a more electronegative atom, the less electronegative atom has to move inwards because its nucleus was previously favorably attracted to the electrons from the other atom.
That means generally, the greater the electronegativity difference between two atoms is, the shorter you can expect the bond to be, insofar as the electronegative atom is the same size as another comparable electronegative atom.
However, examining actual data, we would see that on average, in conditions without other bond polarizations occuring:
r
C
−
Cl
≈
177 pm
r
C
−
C
≈
154 pm
r
C
−
O
≈
143 pm
r
C
−
F
≈
135 pm
r
C
−
H
≈
109 pm
r
O
−
H
≈
96 pm
So it is not necessarily the least electronegativity difference that gives the longest bond.
Therefore, you cannot simply consider electronegativity. Examining the radii of the atoms, you should notice that chlorine is the biggest atom in the compound.
r
Cl
≈
79 pm
r
C
≈
70 pm
r
H
≈
53 pm
r
O
≈
60 pm
So assuming the answer is truly
C
−
C
, what would have to hold true is that:
The
C
−
F
bond polarization makes the carbon more electropositive (which is true).
The now more electropositive carbon wishes to attract bonding pairs from chlorine closer, thereby shortening the
C
−
Cl
bond, and potentially the
C
−
H
bond (which is probably true).
The shortening of the
C
−
Cl
bond is somehow enough to be shorter than the
C
−
C
bond (this is debatable).
