The valves stop the blood from flowing backwards
Answer:
Explanation:
Tenochtitlan was located on a swampy island in Lake Texcoco in what is today south central Mexico. The Aztecs were able to settle there because no one else wanted the land. At first, it wasn't a great place to start a city, but soon the Aztecs built up islands where they could grow crops. The water also worked as a natural defense against attacks from other cities.
Read more at: https://www.ducksters.com/history/aztec_empire/tenochtitlan.php
This text is Copyright © Ducksters. Do not use without permission.
<span>The formation of a derivative being a necessary step in the experiment lies in the importance of the derived structure. Often the derived product confers to reaction pathways which uses less reactive starting materials and more easily proceeds to completion. This also allows us to take a small amount of sample. The derived product at times is a general compound allowing its easy analysis. Often we encounter a product but we find it difficult to analyse it in ways we want. Here lies the essence of forming a derivative which often are simpler compounds allowing easier analysis yet having similar functional groups and structural properties. Also sometimes we encounter problems when our desired product is unstable and forms stable degraded products. But if we somehow manage to synthesize a derivative it may be relatively stable and form no degradation products. It would be stable at least for a significant period of time making it easier to study its properties. The derived product also at times are synthesized using general reaction pathways facilitating a way of easier synthesis and helping it to correlate with other similar reaction pathways and products.So the above paragraph accounts for the need of derivatives. When we encounter problems similar to those mentioned above it becomes necessary for a researcher to form rather synthesize a derivative.</span>
Answer:
0.013%
Yes, it does. The answer agrees with the statement.
Explanation:
Both conformers are in equilibrium, and it can be represented by the equilibrium equation K:
K = [twist-boat]/[chair]
The free energy between them can be calculated by:
ΔG° = -RTlnK
Where R is the gas constant (8.314 J/mol.K), and T is the temperature (25°C + 273 = 298 K).
ΔG° = 5.3 kcal/mol * 4.182 kJ/kcal = 22.165 kJ/mol = 22165 J/mol
22165 = -8.314*298*lnK
-2477.572lnK = 22165
lnK = -8.946
K = 
K = 1.30x10⁻⁴
[twist-boat]/[chair] = 1.30x10⁻⁴
[twist-boat] = 1.30x10⁻⁴[chair]
The percentage of the twist-boat conformer is:
[twist-boat]/([twist-boat] + [chair]) * 100%
1.30x10⁻⁴[chair]/(1.30x10⁻⁴[chair] + [chair]) *100%
0.013%
The statement about the conformers is that the chair conformer is more stable, and because of that is more present. So, the answer agrees with it.
Answer: A
Explanation:
Hydrolysis reactions break down not only feldspars but many other silicate minerals as well, amphiboles, pyroxenes, micas, and olivines.
