Science & Mathematics - 10 December 2007

Any help would be great! Thanks

2007-12-10 12:52:09 · 3 answers · asked by mkpstar10 1 in Biology

2007-12-10 12:51:37 · 12 answers · asked by Anonymous in Geography

What is the coordination number for each of the following.

(a) Na+ in the NaCl structure,


(b) Zn2+ in the ZnS unit cell,


(c) Ca2+ in the CaF2 unit cell

2007-12-10 12:51:22 · 2 answers · asked by Karma564 2 in Chemistry

2007-12-10 12:50:07 · 2 answers · asked by coolio_de_fabio 2 in Biology

Ethanol, C2H5OH, melts at -114°C and boils at 78°C. The enthalpy of fusion of ethanol is 5.02 kJ/mol, and its enthalpy of vaporization is 38.56 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g·K and 2.3 J/g·K, respectively. How much heat is required to convert 78.0 g of ethanol at -127°C to the vapor phase at 78°C? The answer should be in kJ.

2007-12-10 12:49:55 · 1 answers · asked by Karma564 2 in Chemistry

2007-12-10 12:48:22 · 13 answers · asked by Hannah! <3 2 in Earth Sciences & Geology

2007-12-10 12:46:36 · 1 answers · asked by Luke M. 2 in Mathematics

when it says solve
like 4^x+1=8^2x+3


4 and 8 are not the same so does that mean i have to multiplay by two in order to get 8. so that means i have to multiply the exponet by 2 too. right?

2007-12-10 12:45:28 · 1 answers · asked by Ballerina 5 in Mathematics

2007-12-10 12:44:08 · 3 answers · asked by mahal kita<3 1 in Zoology

The atmospheric pressure p on a balloon or an aircraft decreases with increasing height. This pressure, measured in millimeters of mercury, is related to the height h (in kilometers) above the sea level by the formula... p=760e^(-.145h)

Question 1. Find the height of an aircraft if the atmospheric pressure is 247 millimeters of mercury.

Question 2....

2007-12-10 12:40:48 · 2 answers · asked by Dave & Sunny 2 in Mathematics

ok here it is, i'm doing a science project and it's on pH in water but i dont know what pH is, nor if lower the pH in the water the better or the lower the better, these are what i've tested; bottled water:9, aquarium water:10, tap water:12.
if i got them wrong or something please tell me but i just need to know what ph is better, lower or higher? thanks for helping me :]

2007-12-10 12:40:41 · 7 answers · asked by Anonymous in Chemistry

Would it work?
Is it worth the money?
Why might it be a good or bad thing?

2007-12-10 12:38:55 · 7 answers · asked by Chung Island™ 5 in Geography

im in algebra 2 honors and i am studying cirles on the graph.

how does the equation x(squared)+y(squared)=1 make a cirlce??? kinda confusing... because when i put it in my calculator and hit graph nothing happened.

2007-12-10 12:38:11 · 6 answers · asked by Kris2007 2 in Mathematics

2007-12-10 12:36:45 · 6 answers · asked by Anonymous in Mathematics

a blue solid is found to contain 36.84% nitrogen and 63.16% oxygen. what is the empirical formula of this compound?

is the answer NO2 or NO
because im not sure whether to round up or down

2007-12-10 12:36:01 · 1 answers · asked by corndog 1 in Chemistry

Explain why a frame that normally is rectangular will, when it sags, keep the shape of a parallelogram.

2007-12-10 12:35:58 · 5 answers · asked by Sally S 1 in Mathematics

2007-12-10 12:35:48 · 3 answers · asked by cody s 1 in Mathematics

2007-12-10 12:35:30 · 1 answers · asked by Anonymous in Botany

2007-12-10 12:34:43 · 14 answers · asked by Anonymous in Mathematics

why can't we harness electricity from lightning?
In some place that is known for lightning why can't we put up a huge pole. Either for the lightning to hit. Or maybe it could be raised into the clouds. Where the positive and negative charges are. then we could use that charge for electricity.

Now it won't be a constant supply. But neither is wind.

2007-12-10 12:34:26 · 8 answers · asked by Philip Augustus 3 in Physics

2007-12-10 12:34:10 · 9 answers · asked by Artisic 1 in Mathematics

I'm told to solve this equation 9x-4= -9x^2

I'm not too sure how to do it, I tried changing it to standard form but I was lost there since there is no common factor.
If anyone could do the steps for it, I'd appreciate it!

2007-12-10 12:33:35 · 5 answers · asked by Nick B 2 in Mathematics

2007-12-10 12:31:54 · 16 answers · asked by Anonymous in Mathematics

i am modifying my 18v rechargable torch by doing away with the hot 18v bulb and replacing it with a (12x) LED light that im using from a 4.5v headlight torch (the donor torch). so i need to cut the voltage from 18v down to 4.5v.... can i do this with aresistor, and if so, what value should that resistor be? thanks kind people!

2007-12-10 12:31:30 · 5 answers · asked by philo 2 in Engineering

During spring semester at MIT, residents of the parallel buildings of the East Campus dorms battle one another with large catapults that are made with surgical hose mounted on a window frame. A balloon filled with dyed water is placed in a pouch attached to the hose, which is then stretched through the width of the room. Assume that the stretching of the hose obeys Hooke's law with a spring constant of 112 N/m. If the hose is stretched by 4.50 m and then released, how much work does the force from the hose do on the balloon in the pouch by the time the hose reaches its relaxed length?

2007-12-10 12:29:41 · 1 answers · asked by Anonymous in Physics

Ok do the formula is Q = m*c* (delta) t

Q is the specific heat.
M is the mass
C is the What? This is what i need help with.
And Delta ( T ) is the change in temperature i believe?

2007-12-10 12:27:56 · 1 answers · asked by John D 1 in Engineering

-1
15
56
1
which one is it??

2007-12-10 12:27:14 · 3 answers · asked by Anonymous in Mathematics

You push a 1.9 kg block against a horizontal spring, compressing the spring by 16 cm. Then you release the block, and the spring sends it sliding across a tabletop. It stops 80 cm from where you released it. The spring constant is 200 N/m. What is the block-table coefficient of kinetic friction?

2007-12-10 12:26:42 · 1 answers · asked by Anonymous in Physics

what is the link between current land formaton and the earths early history?




~~~~~ALSO~~~~~

how does the earth recycle its crust?



[[i think these are interesting questions..but will you help anser them!! THX ILY~!]]

2007-12-10 12:24:57 · 1 answers · asked by ♥.:ily:.♥ 1 in Earth Sciences & Geology

whats x

2007-12-10 12:22:07 · 9 answers · asked by dedrick h 1 in Mathematics