Science & Mathematics - 19 September 2007

Why do you think it took so long?

2007-09-19 15:09:29 · 2 answers · asked by Moon O 1 in Physics

I must not be doing this right because I'm not getting any of these answers. please help! :(
The problem:

The lattice enthalpy of AgF is 971 kJ*mol and the hydration enthalpy is -993kJ *mol. Estimate the enthalpy of solution AgF.
A) -993kj*mol
B) -971 kj*mol
C) -1964kj*mol
D) +22kj*mol
E) -22kj*mol

2007-09-19 15:06:29 · 2 answers · asked by ___ 1 in Chemistry

2007-09-19 15:04:40 · 1 answers · asked by Updated Life th13f 2 in Chemistry

The rules state that subscripts cannot be added or changed:
However in the question a subcript has been added:
Balance this equation and show in molecular form
lead(II)nitrate+sodium chloride-->
answer: Pb(NO3)2+2NaCl->
PbCl2(s)+2NaNO3
A subscript has been added against Cl in PbCl which goes againist the rules.

I hope somebody can help!!

2007-09-19 15:03:43 · 7 answers · asked by Gideon 1 in Chemistry

2007-09-19 15:03:34 · 4 answers · asked by princess 1256 1 in Chemistry

a) Dick is 3 times as old as his brother, Ben. In eight years' time, the sum of their ages will be 28 years. How old is each one now?
b) I have 2 sisters. The product of their ages is 72. The sum of their ages is 18. How old are my 2 sisters?
c) Greg is 18 years old, 3 times as old as his sister, Janice. In how many years' time will Janice be half as old as Greg now?

2007-09-19 15:00:23 · 1 answers · asked by NinjaX 2 in Mathematics

a. hydrogen
b. cnbon
c. sodium
d. oxygen

2007-09-19 15:00:19 · 3 answers · asked by Anonymous in Biology

A capacitor has a capacitance of 2.3*10-8F. In the charging process, electrons are removed from one plate and placed on the other plate. When the potential difference between the plates is 400V, how many electrons have been transferred?

2007-09-19 14:59:36 · 1 answers · asked by Anonymous in Physics

Find the minimum rate of change of f(x,y) = ln(x^2 + y^2) at the point (2, -3) and the direction in which it occurs.

2007-09-19 14:57:23 · 1 answers · asked by Anonymous in Physics

2007-09-19 14:54:30 · 2 answers · asked by anonamuss 2 in Chemistry

ground. If they are initially d = 9.0 km apart, how long will it be before they reach each other?

_min?

2007-09-19 14:52:39 · 2 answers · asked by sportmatic23 1 in Physics

hey im having major trouble with this geography stuff..can you help me out? i guessed on most can you tell me if their right or wrong and help me if their wrong

1. name three nations that are in east (Asia Korea, China, Japan)
2. Name three nations that make up indochina ( vietnam thailand indonesia)
3.Name 5 nations of the Middle east (iran iraq syria saudia arabi, turkey)
4. Name two nations in eastern Europe (Russia ukraine
5. name three nations in western Europe (Inited kingdom, Ireland, france)
6. Two nations that are in western europe that are also in northern europe (norway, united nation)
7 Name two nations that are in Central Asia

2007-09-19 14:50:33 · 4 answers · asked by liz 2 in Geography

2007-09-19 14:46:53 · 10 answers · asked by slamdunker3 1 in Mathematics

Do you think is possible that we havent gotten any visits from the future because once we reach a certain point of development humans will kill themselves and that would be the end of humanity?

2007-09-19 14:43:26 · 6 answers · asked by wik 2 in Astronomy & Space

I was wanting to know how Genes are copied because I can't find the process anywhere. Is it the same process as DNA?

2007-09-19 14:42:06 · 3 answers · asked by Daphne 1 in Biology

I was told that if a bird ingests disprin it will explode. Is this true, or is this just an urban myth.

(Please be advised that I am not condoning this, wanting to attempt this, or think it is anything less than sick, just wanted to know if it was true)

2007-09-19 14:41:32 · 8 answers · asked by LadyRebecca 6 in Zoology

I don't want the definition of a typhoon. I want the scientific explanation of the differences. THANKS!!

2007-09-19 14:39:36 · 11 answers · asked by Christina 2 in Weather

a) What is the coefficient of static friction between the box and the floor?
b)If the 40.0 N force continues, the box accelerates at 0.70 m/s^2. What is the coefficient of kinetic friction?

2007-09-19 14:39:13 · 1 answers · asked by J L 2 in Physics

Its found in plant and animal cells, but multi-cellular organisms contain different cell types, tissues and organs, and there are many diff. types of organism. Please be specific on what type of cells its found in

2007-09-19 14:38:15 · 4 answers · asked by meeka 1 in Biology

2007-09-19 14:37:01 · 3 answers · asked by Taronda M 1 in Biology

Menthol ( = 156.3 g/mol), a strong-smelling substance used in cough drops, is a compound of carbon, hydrogen, and oxygen. When 0.1595 g menthol was subjected to combustion analysis, it produced 0.449 g CO2 and 0.184 g H2O. What is its molecular formula?

2007-09-19 14:35:47 · 2 answers · asked by neena m 1 in Chemistry

help please!

2007-09-19 14:35:13 · 2 answers · asked by Unique 1 in Biology

2007-09-19 14:33:12 · 10 answers · asked by Anonymous in Engineering

2007-09-19 14:31:30 · 3 answers · asked by patrick e 1 in Mathematics

I'm supposed to be factoring without the quadratic formula. One of the problems is:

7y^2 - 21y +5

2007-09-19 14:30:20 · 4 answers · asked by nimble_rabit 1 in Mathematics

Okay so how can you simply a expression


4a+2b+a


explain to me

2007-09-19 14:29:39 · 7 answers · asked by Anonymous in Mathematics

#1 Specify what ions are present in solution upon dissolving each of the following in water:
a) zinc chloride
b) nitric acid
c) ammonium sulfate
d) calcium hydroxide


#2 Formic acid, HCHO2, is a weak electrolyte. What solute particles are present in an aqueous solution of this compound? Write the chemical equation for the ionization of formic acid.

2007-09-19 14:29:38 · 3 answers · asked by joey 1 in Chemistry

Here is the entire question:

A canon, located 60 meters from the base of a vertical 25 meter tall cliff, shoots a 15 kilogram shell at 43 degrees above the horizontal toward the cliff.

I found the minimum muzzle velocity for the shell to clear the top of the cliff to be 32.6 m/s.

Under these conditions, how far does the shell land past the edge of the cliff?


Thanks a lot for your time!

2007-09-19 14:29:36 · 1 answers · asked by abc123 1 in Physics

2007-09-19 14:29:32 · 2 answers · asked by patrick e 1 in Mathematics

what are these?

2007-09-19 14:27:27 · 3 answers · asked by cosmic_cougar25 3 in Biology