Primarygun

Thank you.The diffraction of a light beam is really different from that of a water wave, isn't it?

Oh sorry, I can't find it again. Do interferences occur when a light passes through a single slit by diffraction? Only one area is bright ? or Several areas are bright projected on a screen?

http://www.geocities.com/thesciencefiles/singleslit/diffraction.html] Refer to this web site, please. The brightness of the colour is proportional to its amplitude? I can understand why the middle of the screen is the brightest, but in my mind, I think there should be only one area which is bright for a single-slit. Is that light has many beams and able to create interference for even only a single-slit? The diffraction of a light beam is really different from that of a water wave, isn't it?

What does coherent exactly mean? What does same phase difference refer to? Why these two factors must be present so as to create interference?

Doesn't the pH value vary as different molarity though the amount of acid molecules is the same?

Neutralization + addition of solution which contains water Dilute the solution Hence, pH value should drop faster.

Yes, but I think I am trapped by a small problem which cannot be answered in that web site though it contains lots of information of titration, such as weak-weak, strong ../

I think that both combination of water molecules fron hydrogen ions and hydroxide ions and the addition of water into the solution speed up the lowering of the pH value. (Acid is adding into a solution of alkali)

Why is the change when some acid is added into alkali very small? Relative to the change around the end point, I can understand it. But, the pH value really drop very slightly, why?

Will some other salts be trapped inside crystals of sodium chloride when we evaporate the solution?

Would you like to explain the curve? What's the nature of methyl orange? How about using excess hydrochloric acid? Then the product would not be contaminated.

I thought of a method to prepare sodium chloride solid. First, pour a certain amount of hydrochloric acid into sodium hydroxide, add a few drops of methyl orange with titration, stop when the colour turns from yellow to red. There are some excess acid mixed with a solution of sodium chloride. Evaporate with steam bath and get the filtrate (crystal), wash it with distilled water and dry it. Is it a good method? Moreover, I want to ask why the change of pH value is very little when an acid is adding to an alkali.

Ya, there are many hydrogen atoms bonded.

I don't know. For the first one, actually, I suspect whether the choices are wrong. For the other, the contents are not in my school's syllabus, so I don't have any idea.

Sorry, just my fault. I am not able to understand it.

I list the question one by one. I hope this is a good arrangment. 1.The blades of a fan is rotating in an anti-clockwise direction. Its motion is frozen with a strobe frquency of 1000 Hz without a change in appearance. Which of the following is not a possible rate at which the wheel is rotating? There are six slits on the fan. A.200 revolution per second. B.500 rev. per second. C.2000 revolution per second. 2.Why the wavelength of a wave increase when it passes from a shallow region to a deep region? Does the amplitude change? 3.Why the wavelength of a wave increase when it passes from a shallow region to a deep region? Does the amplitude change? 4. Why does the wavelength of a wave play a very important role in diffraction? If the wavelength is bigger than the hole passing through, a very circular wave is produced while a very straight wave is produced if the hole is big enough?

Why the coordinates of the vertex are totally different? No triangle is formed?

Is b correct? There should be a reaction force of the friction which act towards left on the 100kg. F-f=net force.

I am thinking about how to calculate the number of years that he can stop paying that.

Find out the rate per month* The money owe after each payment.

In a dicot. plant, where do they store their food from photosynthesis? Roots, Stem, do they store in their leaves? Mesophyll cells?

For a beaker of water containing carbon dioxide gas with a thick layer of paraffin oil on the top, why can't oxygen pass through the oil layer and dissolve into the water but carbon dioxide can diffuse through the layer and reach atmosphere?

Hihi. To find an exact value, is calculus knowledge required?

Ok. Thank you guys.

Sometimes, it would say that stomata rarely open or even close at night. If plants close the stomata at night, how can the plants get oxygen? Are all the stomata fully closed? If not, the problem is simple because oxygen can still diffuse into the plants in a low rate.