Science & Mathematics - 18 October 2007

Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.

a) 9.490 × 1025 Cr atoms
b) 2.248 × 1024 Cr atoms
c) 1.124 × 1024 Cr atoms
d) 3.227 × 1023 Cr atoms
e) 1.613 × 1023 Cr atoms

2007-10-18 06:53:25 · 1 answers · asked by Jennifer W 1 in Chemistry

2007-10-18 06:53:25 · 2 answers · asked by Morgan 1 in Other - Science

box and floor are = 0.190 and = 0.150. The truck stops at a stop sign and then starts to move with an acceleration of 2.22

If the box is a distance 1.79 from the rear of the truck when the truck starts, how much time elapses before the box falls off the truck?
Take the free fall acceleration to be = 9.80
In seconds
How far does the truck travel in this time?
Take the free fall acceleration to be = 9.80 .
In meters

2007-10-18 06:51:46 · 2 answers · asked by Bugz 3 in Physics

I posted this question about 10 mins ago, then realised I couldnt interact with the answers. Sorry for posting again but it's really interesting how the vast majority of people are completely unaware of this. Cow's milk is NOT meant for humans fullstop. It is designed for cows. In fact it is designed for calves. It is so so bad for humans and most of us are lactose-intolerant at birth but get weaned on to cow's milk. It's interesting how we have been completely brain-washed by advertising. The perfect food for newborns is mother's milk, not milk. We are not cows. Just think about it, it's just like giving monkeys dogs' mil and giraffes human milk. It's not right. Cows have 4 stomachs, cows is so not right for our digestive system. I am not a nutritionist but I am very heavily interested and well read in the subject and I will just tell you this: my children used to be permanently ill, runny noses/ fevers/ coughs, all sorts. Since the very day we gave up cows milk, Feb 06, not ONCE ill.

2007-10-18 06:50:35 · 27 answers · asked by Happy 2 in Zoology

what are the differences between t-tests and chi squares?

2007-10-18 06:50:28 · 4 answers · asked by Anonymous in Mathematics

I am just wondering if I got it right on the quiz.

2007-10-18 06:49:32 · 3 answers · asked by ilovesoccer 1 in Mathematics

2007-10-18 06:48:40 · 7 answers · asked by theoneuluv08 1 in Astronomy & Space

When an element's nucleus changes to that of a new element, it is called:

mutation.

radiation.

radioactive decay.

ionic radioactivity.

2007-10-18 06:46:42 · 6 answers · asked by Anonymous in Chemistry

Given:
- Each mole of Fe(CN)6 (4-) loses exactly one mole of electrons in a reaction
- Once you know # of moles of electrons released, you know number of moles of electrons used to reduce...
- n(electrons) = n(Fe(CN)6 (4-))
- Moles after titrations I found were .0005 m, .000196 m

Does anyone know how I can find number of moles of electrons released? I have no idea where to start or what to consider to find the moles of electrons.

Thank you so much for your help :)

2007-10-18 06:46:32 · 3 answers · asked by Miller4Bears6 2 in Chemistry

A 81.5 kg man is riding an escalator in a shopping mall. The escalator moves the man at a constant velocity from the ground level to the floor above, a vertical height of 5.45 m. What is the work done on the man by each of the following forces?
(a) the gravitational force
___J
(b) the escalator
___ J

2007-10-18 06:39:09 · 5 answers · asked by Santina E 1 in Physics

2007-10-18 06:39:04 · 14 answers · asked by Anonymous in Earth Sciences & Geology

having second thought I want them to be happy if I give them a bigger tank them recommended and fallow all other directions will they be happy or just be able to stay alive? Is there a difference to them? I dont want them to feel caged

2007-10-18 06:38:16 · 4 answers · asked by Anonymous in Zoology

Its a science project and I need some help!!
Here are some of the questions I need to answer.
Explain where ash fall fossil beds are and who discovered them.
Describe the steps
Why are they unique?
Any pictures and diagrams would also be greatly appreciated!! Thanks a lot!!

2007-10-18 06:36:12 · 2 answers · asked by catlover 2 in Earth Sciences & Geology

My problem ask? A 10.0ml sample of aqueous HCL requires 24.32 mL of 0.134 M NaOH to reach the endpoint. What is the molar concentration of HCL? The equations for the reaction is

NaOH + HCL -----> NaCl + H2O

2007-10-18 06:35:42 · 4 answers · asked by browneyez4u2c 1 in Chemistry

A projectile of mass 2 kg approaches a stationary target body at 4.9 m/s. The projectile is deflected through an angle of 59.5° and its speed after the collision is 2.8 m/s. What is the magnitude of the momentum of the target body after the collision?

2007-10-18 06:35:35 · 1 answers · asked by angie 1 in Physics

prove sech^2 x + tanh^2x =1 i know that sech = 1/cosh and i know what cosh and tanh equals with the e thing but how can you get them to cancel each other out?

2007-10-18 06:34:35 · 2 answers · asked by Dustin 1 in Mathematics

2007-10-18 06:31:58 · 4 answers · asked by Anonymous in Mathematics

plz reply soon.
i m having a test on the day after tomorrow

2007-10-18 06:31:34 · 4 answers · asked by darling 1 in Chemistry

I cannot find an example in the book like this. Say you have a BJT transistor amplifier (common emitter) configuration WITHOUT the bypassed emitter resistor. When you take into the account the parasitic capacitance, you use the miller effect to drop Ccb down to the base to ground and the collector to ground. If the emitter resistor WAS bypassed, you would add these miller-capacitances to their closest parasitic capacitance since they're in parallel, right? Well since the emitter resistor ISN'T bypassed, you should treat the two separate to find the break frequencies (1/(2*pi*C*Rthevenin)) since they're not in parallel and you can't combine. IS THIS CORRECT? BY "THIS" I MEAN TREATING THE MILLER AND THE PARASITIC CAPACITANCE SEPARATELY AND GETTING MULTIPLE BREAK FREQUENCIES?

2007-10-18 06:29:24 · 3 answers · asked by rrossorr 3 in Engineering

2007-10-18 06:28:46 · 6 answers · asked by damanjd1 2 in Chemistry

if so, what if one of them commits a crime and they have to use dna, how will they know who did it?? Just curious...

2007-10-18 06:28:34 · 32 answers · asked by mstlight 2 in Biology

2007-10-18 06:26:59 · 4 answers · asked by Krys F 1 in Mathematics

how can i make (1+cosx)/(1-cosx) be equal to (cscx + cotx)^2 ???????????????????????????

2007-10-18 06:26:05 · 4 answers · asked by Anonymous in Mathematics

Is there a way to desalinate sea water that doesn't require any sophisticated power resources?

2007-10-18 06:23:30 · 4 answers · asked by MoRmEx 5 in Earth Sciences & Geology

Oxalic acid, H2C2O4, reacts with the chromate ion in acidic solution as follows:
H2C2O4(aq) + CrO4-2(aq)------>CO2(g) + Cr+3(aq)
What is the molarity of the oxalic acid solution if 10.0mL of this solution consumes 50.0mL of 0.0350 M CrO4-2? Could you guys please show the work step by step? Thank you

2007-10-18 06:22:52 · 1 answers · asked by Sky N. 1 in Chemistry

I know that most physicists and cosmologists accept that they probably do exist and work on that basis, but do we know for a FACT that they are there. For example, have we actually seen one?

Or are they still fundamentally theoretical in the same way that Big Bang and Relativity are?

Please only answer if you know for sure. This is to settle an argument, and a dinner for two at Berni Inn rests on it.

Thank you :-)

2007-10-18 06:22:50 · 22 answers · asked by Ms Minger 3 in Astronomy & Space

18th night 10:40
i jus went into the balcony, and saw a red moon. it was too red that it looked exactly like mars. i thought to capture it through camera but it was gradually going down and a building was covering it. i could only see it for 10 mins. not more than that. it was a very good sight. but was it mars or the moon? if it was the moon why was it so red? but it was as big as moon. after 10 more mins it jus went down completely.

2007-10-18 06:21:51 · 5 answers · asked by MelodyMoon 3 in Astronomy & Space

I need this for science...... i need website that I can use to look up organic and inorganic food, nd i need info on the contriversy between the two.... can someone please help???

2007-10-18 06:21:47 · 5 answers · asked by Anonymous in Biology

2007-10-18 06:21:13 · 5 answers · asked by Anonymous in Mathematics

if the amplified product of pcr contains an invariant Alul site. How is the presence of this site an advantage for genetic diagnosis of the mutation?

2007-10-18 06:20:24 · 4 answers · asked by Anonymous in Biology