dttom

here's a question I would like to ask, any could help would be appreciated. http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=/798fscd&.dnm=8900scd.jpg&.src=ph

I would like to ask two questions... the first one is about rheostat, which its resistance could be changed. R=V/I, when R increases, three cases are possible, V increases while I keeps constant; I decreases while V keeps constant; and V increases while I decreases at the same time, which of them is the case? http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=798fscd&.dnm=3d31scd.jpg&.src=ph the experimental set up shown in the above diagram is used to find out the relationship between resistance, voltage and current. when a current pass through the rheostat current and voltage decreases as the rheostat consumes enery, the current then flow through the other resistor and the current after the passage is recorded, however, as the resistance of the rheostat varies, the current to the resistor varies also, which would seem to affect the current reading after passing through the resistor, then the question is that would this change in current by the rheostat affect the experiment result?

i think the carbon dioxide is first entered the erythrocytes and be changed to hydrogencarbonate then is released back to plasma.

An experiment is carried out to show that xylem is responsible for the transportation of water in plant. A plant which soil on roots has been removed is used in th eexperiment. The roots of the plant are bathed in a stained solution, after three hours, thin cross sections on stem, roots and leaves are cut and the sections are examined under microscopr. Red stain substances are found in where xylem is located. It is claimed that xylem is responsible for the transportation i plants then. However, I would like to ask, whether experiments which show that the stain is not related to the water uptake through xylem are necessary to be carried out before the conclusion is made? That is, is it a must to show that the stain is independent from the water uptake through xylem before the conclusion is made?

I have a related question, could I know how we determine how strong the reagent adsorbs to different transition metal?

I would like to ask would the same electrode dipped into different electrolytes affect its electrode potential, say, would the electrode potential of Zn/Zn2+ differ when Zn electrode if dipped into sodium chloride solution instead of 1M Zn2+ solution? And I would like to know how cathodic protection work. I was just told that during the process, metal article to be protected is connected to the negative terminal of an electrochemical cell making it as the cathode, as electrons flow from the negative terminal to the positive terminal (the metal article be protected), it prevents the article being corroded when exposed to moist air. Afterward, oxygen receives the electrons and react together with water to form hydroxide ion; on the other hand, let the anode in the electrochemical cell as zinc, zinc continuously loses electron to form Zn2+ ion. Howeve, there would be excess positively charged ions accumulated in the cell, while the negative hydroxide ions outside the cell is impossible to get into the cell and neutralize the charge unbalance in the cell, and there would also be a excess negative charge outside, how would this be solve?

It is known that refraction occurs when wave pass from, say, deep water region to shollow water region, and wavelength of the wave decreases and hence the speed of the wave. I would like to know why this would occur in detail. I can't find any expanation in text book, and I was just told that it would occur. And beside, we all know that nuclei of atoms are composed of protons and neutrons, I just know that the reason of why neutrons and protons would be packed together is related to somewhat about nuclear force though I don't know the detail = =...

We all know that silicon dioxide is in giant covalent structure, and atoms are joined together by strong covalent bonds. While we silicon dioxide dissolves in concentrated sodium hydroxide,SiO2 + 2OH- --> SiO32- + H2O I would like to know the processes involved in detail and how can this be done in molecular level. Beside, it is known that C60 is a very hard material, and it is in sphere shape, I would like to know is there any bond between C60 molecules so that C60 could be observable to our naked eyes (I have not ever seen C60).

Allosteric enzyme is an enzyme which has an allosteric site where proteins or substances could bind to and alter the function of the enzyme (cause changes in active site of the enzyme). Negative feedback is an action which resist the change in a system caused by outside environmental factors. For instance, if your body temperature is 0.5 degree celcius higher than your normal temperature, you start sweating to reduce energy gain. And, would you mind don't use words like ordering others to serve you?

I get this point now, but what about the second question? As there is just very little amount of lead(ll) sulphate dissolved, would the barium sulphate is so little that we can't observe?

We all know that even so called 'insoluble salt' would dissolve a bit in water forming a saturated solution. For example, PbSO4, how could we test for the sulphate ion inside? I've asked my teacher about this question, he suggested adding enough amount of lead(ll) sulphate to a certain volume of water forming a saturated solution then filter the excess solid and then test for the ions by using the solution. Now I've got two questions. As there is an equilibrium between solid lead(ll) sulphate and the soluble mobile ions, PbSO4(s) + (aq) <----> Pb2+(aq) + SO42-(aq), as the solubility of lead(ll) sulphate is quite low, 0.99g per 100 ml water, we may expect that the equilibrium constant for the above equilibrium may be quite small, if we filter the excess solids added to water by filtration, that is, remove the reactant of the above equilibrium, I would expect the equilibrium position to shift leftwards, that is, forming back solid lead(ll) sulphate, is my expectation correct? Beside, in spite of whether the equilbrium would shift leftwards, as the amount of originally dissolved PbSO4 is very small, if we just add acidified BaCl(aq) to it as usual, could we observe the result (as I think the amount is so small that I can not observe)?

may be you need to stain the sulphuric acid to demostrate it diffuse on the agar block, by universal indicator, or any other stain, I think.

But how the food in stomach counld slow the effect of alcohol?

H2S + 2NaOH --> 2H2O + Na2S mole ratio of H2S:NaOH is 1:2; 2.05g H2S: 2.05/(2+32)mol=0.06mol; 1.84g NaOH: 1.84/40mol=0.046mol; so 0.023mol of H2S is reacted, mole ratio of H2S to Na2S is 1:1; 0.023mol of Na2S is formed, =0.023*(23*2+32)=1.794g

I would rather believe it is caused by the environment. A previous report said that male with lots of elder brothers would have a higher possibility to suffer, due to the immune system of mother. For the first time of the mother pregent, 'male substance' enter the mother's body while her immune system can not do much on it, while in later pregnacies, her immune system may work aganist the 'male substance', for example testosterone, and thus cause the expression.

well, what about the outstanding stability of the element Pt?

The electron configuration of V is [Ar] 3d3 4s2 and Cr is [Ar] 3d5 4s1, the electron in 4s subshell is transfered to 3d subshell for extra stability, stability by the half-filled 3d subshell. And Ir is [Xe] 4f14 5d7 6s2 while Pt is [Xe] 4f14 5d9 6s1. Mt first question is why Pt's configuration is like that but not [Xe] 4f14 5d8 6s2, how can the electron in 6s subshell be transfered to 5d subshell, in case of 5d subshell is either half-filled nor fully filled? And one more question, where does the stability of Au and Pt come from?

yes, alkalis are soluble bases, then for example, calcium hydroxide, which is slightly soluble, then do we regard the soluble part of calcium hydroxide to be alkali, that mean do we regard calcium hydroxide as a strong alkali?

And is there any difference between strong base and strong alkali?

Alloys are mixture of metals, metal A exists in the space between metal B particles. I was told that mercury can form alloy with most metals while with an exception of iron. So I would like to know why it can't form alloy with iron, but others.

protonated? That means the attachment of H+ to particles.

Solubility is not something absolute, some of the Fe(OH)2 can be dissolved and result an alkaline solution as the present of OH-.

I don't think so, thermophiles usually live in places where higher than 45 degree celcius, I think the human body is not a suitable host for them.