# Chap

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36

1. ## Mystery of Homosexual Behavior

Cannot homosexuality be the result of a recessive gene or set of genes surviving through the ages? Compare this with the case of an albino animal. In humans as well as in many other vertebrate species, there are several albino organisms existing within that species. They exist, even though they are at a disadvantage in the wild (obviously humans who have albinism are not at such a disadvantage because we don't live in the wild). Just like that, isn't it possible that the genes which may (directly or indirectly) lead to homosexuality be present within the human-gene pool, affecting only a small number of humans at a time, but present, nevertheless?

find the number of moles of methlybenzoate(let's call the result A). Then find the number of moles in 5cm3 of NaOH(let's call the result B). Write out the balanced reaction equation between NaOH and methlybenzoate. Use the ratio between the methylbenzoate and NaOH to calculate the number of moles of NaOH required to react completely with the methlybenzoate (result A). Check whether this result is greater than B. If so, NaOH is NOT in excess.
3. ## Help in identifying organic compound?

Question: The compound P has C,H,O and N as elements. A white pp+ was formed when P was acidified. Identify a structural feature of P which caused this precipitation. I was thinking on the lines of: maybe its an ammonium salt of long chain carboxylic acid [e.g.- (CH)5COO-(NH4)+]. When a strong dilute acid is added, the carboxylic acid will be formed and since its a long chain molecule, it will precipitate out of the solution? Am I right or is it some other obvious compound? Thanks for answering.
4. ## Oxidizing and reducing regions of Bunsen burner flame

Which part of the Buunsen burner flame is oxidizing? According to wiki.answers and my university course book, it is the 'Inner cone': http://wiki.answers.com/Q/Oxidizing_zone_in_the_Bunsen_burner_flame but according to the following websites/files, it is the outer cone: http://eso.vscht.cz/cache_data/1061/www.vscht.cz/ach/pub/LAChI-manual.pdf http://chemistry.about.com/library/weekly/aa010102a.htm This is not homework, I'm studying for my finals and this got me confused.
5. ## Electrolysis of brine; unexpected result

yes, anode is (+) and the cathode is (-), I didn't make a mistake on the electrodes. Also, I don't think oxygen evolved at the anode (+) since the solution was almost saturated with NaCl. It is the cathode which eroded and not the anode. I did collect the gas that evolved from the anode and it is definitely chlorine gas (it had a slight yellow green color and pungent odor). I don't know whether it's possible for some oxygen to have evolved, but that's beside the point since it's not the anode which eroded, but the cathode. This is the puzzling question. As for the brine solution that I am using, it is table salt brine not sea-water brine, but a slight precipitate still forms. I'm living in Sri Lanka (a developing nation), where salt is extracted from the sea. I'm not that aware of the exact refining process employed by our country, but maybe the table-salt in Sri Lanka s not as refined as table-slat in developed nations.
6. ## Electrolysis of brine; unexpected result

I electrolysed a brine solution using graphite electrodes. No attempt was made to minimize the chlorine (produced) reacting with the electrolytic solution. After a few hours, a white sludge (possibly Mg(OH)2 and Ca(OH)2) was formed, as expected. This was removed and the electrolysis was continued. After a few hours, the graphite cathode started to flake off. The anode remained intact. This is surprising since I don't think hydrogen reacts with carbon under these experimental conditions. I initially thought maybe the Chlorate ion formed due to the dissolution of chlorine in the solution reacted with the graphite cathode, but that doesn't explain the fact that the anode remains intact. Have I overlooked a simple fact?
7. ## Haber process alternative catalysts

Thank you for your replies!
8. ## Haber process alternative catalysts

Iron is probably the only catalyst used in the Haber process, today. Why aren't any other transition metal catalysts used for this process? osmium and ruthenium aren't economically feasible, but what about other transition metal elements such as Nickel or Copper? Is there a specific reason why Iron is the most suitable catalyst for this process or is iron the cheapest substance that can be used for this process? Another fact to consider is; Iron is one of the chief components in nitrogenases, the group of enzymes used by particular biological organisms to convert dinitrogen into ammonia. Is it probable that the biological organisms use iron in their enzymes because evolution has proved it to be the one of the most efficient catalysts compared to other transition metal elements? I would like to know your views. Thanks.
9. ## stream of water falling down from a faucet

A stream of water falling down a faucet will experience the force of gravity which makes it accelerate. As its velocity increase, in order to conserve its volume, the stream will get narrower, as it travels down. My question is; is that the only reason why the stream gets narrower when it is falling from a faucet? Water molecules can form relatively strong hydrogen bonds and also the stream experiences air resistance. Don't these forces also contribute to the stream of water getting narrower as it flows down? Thanks.
10. ## Are genetically engineered products considered to be man-made or natural?

You seem to have brought another perspective to the argument. I should think about that one; the distinction between artificial and man-made.
11. ## Are genetically engineered products considered to be man-made or natural?

Take genetically engineered tomatoes for example. The genes are modified yes, but the plant grows similar to a natural tomato plant, obeying the same basic laws of nature (photosynthesis, transpiration, growth ect..). However, the product is not exactly natural. So, can the product be categorized under the man-made section or natural section? If you deduce that the answer is "both"; then there is another question: What about other "man-made" materials in our world. Take the laptop for example. Yes, certainly man assembled the parts together, but the whole process had to obey the laws of nature. The parts had to be fitted according to natural laws; so that the whole thing would work. We call these things man-made because man used his intelligence to combine his labor with materials in "a state of nature" (such as iron ore or crude oil from which plastic is made) to make new products. Which is what is happening in genetically engineered tomatoes as well. Man combines his labor with a cell of a natural tomato and makes it into a product. These are just my thoughts on the subject. I may be wrong; and if so; I'm glad to be corrected. I appreciate everyone's thoughts on this subject. Thanks.
12. ## What exactly causes a bicycle to stand upright?

There seems to be some controversy around this topic. I initially thought that it's the gyroscopic effects keeping it upright ( which was supported by the fact that a bicycle may roll downhill by its own), but then I met the argument that those effects are not very strong. I agree with this argument because I think the gyroscopic effects felt by the bicycle is sufficient enough to support a riderless bicycle, but not one with a rider. I mean, a bicycle just weighs a few kilograms, but I weigh 60kg! So the effect it not powerful enough to support me. Am I correct? I came across another theory that; "our brains learn to keep the bicycles upright by making necessary adjustments unconsciously to balance the bicycle." I partially disagree with this theory since I don't believe that our brains are responsible for the whole balancing act without any help. If this theory is true, I should be able to keep a non-moving bicycle upright. I can't balance a non-moving bicycle for more than a few seconds (no matter how much time I spent practicing) , but I can ride for hours on a moving bicycle. I'm sure something else is involved, but can't exactly find it. I would like to know your views. Please state it in simple terms; I'm a biochemistry undergraduate; physics is not my area of expertise. Thanks.

14. ## Why are plants green?

The SIMPLE reason why plants are green is that it didn't need to be any other color! Evolution of an organism depends upon the selection pressures that the organism experiences. So initially the chemical chlorophyll would have evolved in plants, which doesn't absorb green light. Why didn't some chemical which absorbs all light, even green light (let's call it blacknophyll) evolve? Well, as others have pointed out, chlorophyll might have been a simpler molecule (which can absorb just the right amount of energy without breaking a apart) than "blacknophyll". However, down the evolutionary line, there was very little need (selection pressure) for the plants to evolve a completely different kind of molecule, to capture light better. Any inefficiencies in leaves (with respect to capturing the light energy) of primitive plants would have been eliminated (or minimized to significant degree) by simple evolutionary traits, such as increasing surface area etc... But the process was never SO inefficient that a whole new molecule needed to be found. Instead, the selection pressures put on plant were mainly based on factors like reproduction and growth. That's my thought on this. I welcome any corrections on this post; from anyone.
15. ## Photosynthesis vs. solar cells

Yes, you are right. The article provides experimental data showing that in most cases; the solar cells are much more efficient than photosynthesis. The reason for this (according to the research article) seems to be that plants never evolved to have the highest efficiency rate in capturing the sun's energy. Instead, the selection pressures experienced by plants have been mostly on reproduction and growth. However, it may be possible to genetically modify the "leaves" so that they can capture much more light energy. So it is a future possibility. I guess.
16. ## Photosynthesis vs. solar cells

Which is more efficient at utilizing light energy, solar cells or the photosynthesis reaction? I was just wondering whether we may one day be able to utilize photosynthesis directly, for the production of electrical energy (I know that photosynthesis doesn't produce electrical energy, but it could be converted to electrical energy through suitable apparatus). Everyone's thoughts are welcome!
17. ## entropy of an adiabatic expansion?

Thanks for clearing it up!
18. ## entropy of an adiabatic expansion?

If an ideal gas undergoes a reversible adiabatic expansion, then the entropy change would be zero, since reversible heat exchange is zero. What happens if the gas undergoes an irreversible adiabatic expansion? I know, since its irreversible, the entropy should increase, but my undergraduate chemistry course book argues that since entropy is a thermodynamic function, it doesn't depend on the path; so should be equal to the reversible one: zero? Can anyone shed some light on this issue? Thanks!
19. ## Ideal gas problem?

Thanks. However M should stand for "molar mass" right? Not "relative molecular mass", in the second equation?
20. ## Ideal gas problem?

yes, you're right, PV=nRT is the ideal gas equation., but that equation I gave is used in deriving the ideal gas equation, is it not? is that it? Am I looking in the wrong direction?
21. ## Ideal gas problem?

I know the ideal gas equation (and how to derive it):PV= (1/3) x N x m x (U)^2 where: P-Pressure, V-Volume, N- number of molecules, m- mass, U- mean speed of molecules. The problem is my book gives a "different" version of the equation:PV= (1/3) x n x M x (U)^2 where: P-Pressure, V-Volume, n- number of moles, M- relative molecular mass, U- mean speed of molecules It goes on explain that: the relative molecular mass (M) of any substance expressed in grams contains the Avogadro constant number of molecules. That is: M = m x (Avogadro constant). Is this equation (and explanation) correct? I can't find a website which gives a suitable explanation. Can anyone please give me a link or any useful information?Thanks.
22. ## Is a time machine possible?

ok, now I'm really confused!!! What was all the excitement about, if it was not confirmed that particles can indeed travel faster than c? http://www.guardian.co.uk/science/2011/sep/22/faster-than-light-particles-neutrinos
23. ## Is a time machine possible?

There is this video clip on Youtube saying that its possible to make a "time machine", which it claims allows us to travel into the 'past' (not only back in time). I have given the link below: I see several flaws with this video, so please check whether my arguments are correct: 1)The video has been posted before it was confirmed that particles can indeed travel faster than the speed of light, so obviously they didn't have that information at the time. Viewing the video in that context: The argument of the coffee bean doesn't make much sense to me. I mean; when the coffee bean (or whatever) approaches the speed of light, its weight would approach infinity. Therefore, even all the energy in the stirring motion will not be sufficient to make the coffee bean move faster (since any practical engine will fail somewhere before infinity, no matter how close to infinity it can get). 2)I also can't quite understand how Blackholes allows us to go back into the past (not 'time'). Its reasonable to assume if a particle can go faster than light, then "time" will reverse itself for that particle, but how can that particle go back into the "past"? For example, let's say I step into a machine which can travel faster than light and I start travelling. Depending on how much faster than light I travel, "I" will get younger, while everything around me will get older, right? When I step out (say 2 seconds later), I would have grown younger than when I initially stepped into the machine, while everything else around me would have aged naturally. So I would have gone to the future (kind of), not into the past? Please convey your ideas on this matter. P.S physics is not my area of expertise, therefore forgive me for missing obvious details.
24. ## Pain

yes, the concentration of nerves in the body, the pain threshold (the point at which you begin to feel pain) and possible nerve damage all are contributing factors in this case. Another important factor is the tolerance of different individuals to pain. MRI scanning has shown that in people who are very sensitive to pain, the parts of the brain involved in: 1) feeling the intensity of pain and its location ( the primary somatosensory cortex) 2) processing the unpleasant feelings of pain ( anterior cingulate cortex ) both show high level of activity. In people who show low sensitivity to pain, these areas of the brain do not show high level of activity. So the brain also plays an important part in feeling pain.
25. ## Reversible process in thermodynamics?

My undergraduate chemistry course book states that the process: "Two blocks of iron of different temperature are brought into closer contact and thermal equilibrium is attained" is a "reversible" process. I don't exactly understand how this can be, since the process will not occur in the reverse direction spontaneously (i.e the previously warmer block will not get heated up again with respect to the other block, spontaneously). I cannot find any suitable websites that give a good explanation on this matter. I'm sure that I'm looking in the wrong direction. Just direct me in the right direction, I don't need the answer. Thanks.
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