Science & Mathematics - 24 September 2006

2006-09-24 17:12:49 · 11 answers · asked by tom j 1 in Zoology

the monitor of computer or TV screen has got three lights then how we see all the lights can it mean these are the only main lights while others are their derivatives or combinations?? How different wave lengths are combined??

2006-09-24 17:12:37 · 7 answers · asked by kangkan p 1 in Physics

A groundwater contains 1.8 mg/L of iron as Fe 3+. What pH is required to precipitate all but 0.30 mg/L of the iron at 25 C?

2006-09-24 17:11:16 · 2 answers · asked by HH 1 in Chemistry

like - PCl3

They both have negative charge. So you have to put the prefixes instead of balancing them right?

2006-09-24 17:11:09 · 2 answers · asked by gogogo 3 in Chemistry

does it have something to do with density?

2006-09-24 17:10:13 · 4 answers · asked by skippn_star 2 in Chemistry

2006-09-24 17:09:26 · 4 answers · asked by Jessie S 1 in Astronomy & Space

Consider the reaction N2(g) + O2(g) 2NO(g), for which Kc = 0.10 at 2,000ºC. Starting with initial concentrations of 0.040 M N2 and 0.040 M O2, determine the equilibrium concentration of NO.

a) 5.4 × 10–3 M
b) 0.0096 M
c) 0.011 M
d) 0.080 M
e) 0.10 M

okay I keep getting 0.013 which isnt even on here, maybe im doing a significant digit error, and its C?

I set the problem up like this [NO]^2/[N2][O2]=.10

I know N2 and O2 are .040 so multiply .040 with .040 = .0016, multiple .0016 with .10 to get rid fo the denominator so the problem is now. [NO]^2 = .00016 take the square of both sides to get the concentration of NO = 0.0126 = 0.013 M??

2006-09-24 17:05:05 · 2 answers · asked by hmmm 2 in Chemistry

Its our project so it can be as simple as possible. but we were just having a problem with letting the calculator decide to display the difference if the subtraction sign was pressed and the sum if the addition sign was pressed. Please help us

2006-09-24 17:01:42 · 4 answers · asked by chronoel 1 in Engineering

A and B are position vectors relative to and origin 'O'.

vector A is 4i + 14 j, and vector B is 12i + 2 j.

C lies on AB and position vector is 2t i + t j.

find the value of 'k' and the ratio of AC : CB.

thank you for your coorperation with me. the easiest way is going to get 10 points.

2006-09-24 17:01:22 · 1 answers · asked by free aung san su kyi forthwith 2 in Mathematics

If not, do you think that it is possible? I herd that alfa waves are just like radio waves but just harder to pick up.

2006-09-24 17:00:10 · 6 answers · asked by Jay-V-Dub 3 in Engineering

I have recently reread "A Brief History of Time" by Stephen Hawking and in the book, he states that quantum mechanics and relativity are contradictory to each other and therefore cannot both be correct. I realize that at present physics lacks a unified theory that incorporates both but in what ways are they contradictory to each other? And if they cannot both be correct, how is it that we are able to make incredibly accurate predictions using both? Does it have to do with the presence or lack of singularities within the Universe?
Thanks in advance.

2006-09-24 16:59:54 · 5 answers · asked by Anonymous in Physics

1. what is semiconductors

2. why metals are good conductors of electricity while semiconductors have relatively poor conductivity?

3.why plastic deformation(eg. cold rolling) and alloying (eg. in stainless steel) affect the electrical resistivity of metals?

4. what is the difference between intrinsic and extrinsic semiconductor?

5.what is the role of doping in the electrical conductivity of semiconductors

6.what's the difference between n-type and p-type semiconductor?

7.what cause the different resistivity values of metals?

8.why semiconductor possess different electrical resistivity?what is the most dominating factor?

2006-09-24 16:54:23 · 4 answers · asked by lkamh 2 in Physics

Theres no "phillips" or "standard" head to it, and its not threaded, so it doesnt screw in, they're punched in, so why doesn't it just come right back out ?

2006-09-24 16:53:54 · 3 answers · asked by Anonymous in Engineering

It's K2O.

K has a charge of +1
O has a charge of -2

The answer is potassium oxide right? (since one of them is positive and the other negative)

----------------------
SO THIS IS MY QUESTION:

then P Cl3

P has a charge of -3
Cl has a charge of -1

is the answer
#1 - phosphorous trichloride?
#2 - phosphorous chloride?

I got #1...

But my teacher's answer key said #2. Why?
(There were no prefixes for NEGATIVE balanced compounds. is this allowed?)

2006-09-24 16:52:45 · 4 answers · asked by gogogo 3 in Chemistry

My first question is figure out moles and atoms. Just give me the basic information about how to figure out questions that pertain to moles, atoms, and molar mass.
My second question is can you give me a list on how to go grom cm to meter to km, etc and ml to liters, etc

2006-09-24 16:50:58 · 6 answers · asked by clementine576 2 in Chemistry

1.899x10exp-4 mol of an unidentified gaseous substance effusesthrough a tiny hole in 81.1s. Under identical conditions, 1.664x10exp-4 mol of argon gas takes 88.5s to effuse.

2006-09-24 16:50:15 · 2 answers · asked by Brain P 1 in Chemistry

You can't reply with; The unknowable. Be more elaborate.

2006-09-24 16:48:25 · 14 answers · asked by sandwreckoner 4 in Other - Science

2006-09-24 16:47:05 · 8 answers · asked by drastik_211 1 in Astronomy & Space

A and B can do a piece of work in 18 and 12 days respectively. they begin together, but B leaves 3 days before the completion of the work. In how many days is the work finished?

2006-09-24 16:46:06 · 6 answers · asked by wud_luv2know 1 in Mathematics

Zn+HCl----->N2 + H2O

2006-09-24 16:46:04 · 5 answers · asked by Anonymous in Chemistry

2006-09-24 16:45:24 · 6 answers · asked by belinda c 1 in Mathematics

If a ball is thrown into the air with an initial velocity of 48 ft/s, then its height (in feet) after t seconds is given by y=48t-16t^2 . Find the velocity when t=2.

2006-09-24 16:41:03 · 6 answers · asked by Anonymous in Mathematics

2006-09-24 16:39:23 · 9 answers · asked by shy_vi3t_gur1 2 in Chemistry

2006-09-24 16:38:50 · 4 answers · asked by nanajmee 1 in Physics

2006-09-24 16:33:16 · 7 answers · asked by Frank C 1 in Other - Science

2006-09-24 16:31:26 · 2 answers · asked by yokevi_d_1316_2000 1 in Zoology

Can anyone prove that the set of real numbers between 0 and 1 is uncountable?

2006-09-24 16:31:23 · 9 answers · asked by Meder 2 in Mathematics

i mean can you feel the heat

2006-09-24 16:28:55 · 12 answers · asked by master apple 2 in Astronomy & Space

i am doing a lab for chemistry and the question is "cooking involves both physical and chemical changes. give examples that support this statement." I can't think of anything that is a chemical change...i know its probably really easyy...but i really need help!

2006-09-24 16:25:19 · 14 answers · asked by Quechyyy 2 in Chemistry

2006-09-24 16:25:06 · 4 answers · asked by The Knowledge Server 1 in Other - Science