Primarygun

I don't know why my computer has two different ips.

When I check my ip in the control panel, I see one.

When I browse http://www.ipchicken.com/ , there's another one for me.

What's the matter?

You may assume the weight of the sample.

Just say : Let the sample be 100 g

But don't miss the unit for the below, such as mol, ....

This is the problems on the 46th International Mathematical Olympiad.

My friends got excellent result from it, some of them are still very young, the youngest is 2 years smaller than me. That could depress me much. [as I even could not get the qualification to join the competition]

http://gifted.hkedcity.net/Gifted/ActReview/imo2005Mexico/pdf/1dayenglish.pdf

http://gifted.hkedcity.net/Gifted/ActReview/imo2005Mexico/pdf/2dayenglish.pdf

Daves gonna beat you for that.......

Why does DAve gonna beat me?

In that case, I am an ignorant to suggest that silly method, sorry.

I bought a small torch light bulb one hour ago as my old one was faulty after I connected it to a 15V battery.

Now, it is quite different from my old one, not exactly the same in some manners.

For the old one, it can endure a voltage of 2.4V and so does my new one.

However, a label " 0.8A" was on the old one but "0.5A" is on the new one.

What does it mean? I guess it probably is the ampere of current passing through the circuit with a voltage of 2.4V with the presence of this bulb. I guess so.

By the way, I have no idea on which bulb can give a brighter light.

I think the new one could be brighter as the resistance is higher, am I correct?

Yours is a good method. There is a similar problem using your method to figure the solution in my local mathematical olympiad

My method is to express the right hand side with the base 3.

Then using [Math] log [/Math] can find the answer.

Dave, don't worry, you always get the right answer.

Here's an another problem.

Why can't I edit my post?

Try to keep your mind on thinking some trivial things in Maths.

If a wave with wavelength 1.5 cm and frequency 8Hz, is viewed through a stroboscope with 6Hz, what's the change of its wavelength?

My answer is not identical to what in my text book.

My thought is :there is no change of the wavelength, as the time given is enough for the wave to move over one wavelength.

oh ya, I forgot to put back the S.

The one saved Tom cruise by pulling him down was a Japanese? Was he going to destroy the robots?

I was made to accept the [a1,a2,a3]

The latter.

I haven't learnt Sigma yet, so I skip it here.

Let [Math] S=1+r+r^2+r^3+.....[/Math]

then [Math]rS=r+r^2+r^3+r^4+.....[/Math]

That's some problems. Oh, I think there should be a range for r considering what in your photo is.

[Math]rS-S=S(r-1)=-1/ (r-1)[/Math]

where I assume [Math]|r|<1[/Math]

I hope this can help you

Aqua regia is one of the most powerful dissolving agents. It can dissolve very unreactive metals like gold and platinum.

thank you

Ogg Vorbis is a new audio filetype, I think. It is made to fight against mp3, that's my fancy again.

wav file type can be played by a normal CD player but mp3 cannot.

Does anyone know whether ogg vorbis have this function?

That entertains me. We can talk Cantonese here!

Bettina, how did you get those words? I don't get it.

ps2huang, I think english grammar is not very difficult but it is too difficult for us to have a voice like an American's or British since we didn't learn from a foreign teacher when we are in our childhood.

Does alcohol react with ammonia? I poured some into my toilet. The stinky smell comes from the flushing water.

It is not very toxic as mercury liquid does not normally dissolve in blood and is transported slowly ?

Are you a Chinese or currently learning Chinese?

We also know how nasty chlorine is, too, and it is used in our drinking water more often.

But, we are not breathing in chlorine.

Recently, there was a news about mercury in thermometer in my region.

A lady broke the thermometer and syringed the mercury into her arms.

Finally, she was discharged later.

Some experts mentioned if she inhaled some mercury vapour, she would have a higher chance of getting closer to death. The doctors who attempted to save the woman's life suited theirselves with protective coats like those wearing to engulf SARS.

Damage to lungs is always more serious than damage to our alimentary canal.

"said Mary' date='" does it mean which was said that was Mary?

"said she' should be used as "said her," right?[/quote']

Mary said it.

I don't know whether replacing "said she" with "said her" is wrong.

How many gold metals are given in every International Physics Olypiad Competition?

The lack of practice in laboratory reactions frustrates me from helping you.

Therefore, I could only suggest some ideas that I am certain of them.

To have tetraaminecopper(II) ions, you have to have excess ammonia, so that the precipitate copper (II) hydroxide produced from the precipitation reaction can dissolve by forming complex ion(tetraaminecopper(II) ions).

If I am right, with my correct calculations, I don't think you are having excess ammonia.

Assuming all the precipitates dissolved and a deep blue solution comes out,

you may get

Cu^2+(aq) + 4NH3 (aq)---> [Cu(NH3)4]^2+ (aq)

This time, ammonia is a limiting agent, so finding the total amount of NH3 has reacted, so that you can find the amount of tetraaminecopper(II) ions formed.

Then, one tetraaminecopper(II) ions will bind with one sulphate ion and one water molecule, then you can get it.

But, in this case, I'm afraid the experiment cannot succeed as there are still some excess copper(II) ions, you need to precipitate them first.

Or maybe my calculation is wrong!