Science & Mathematics - 14 November 2007

A radioactive element sodium-24 has a half-life of 17 hours and is used to help locate obstructions in blood flow. A procedure requires 1.2 grams and is scheduled to take place in 24 hours.

At what rate is the sodium-24 decaying?

What is the minimum amount of sodium-24 that must be on hand now?

2007-11-14 17:34:50 · 2 answers · asked by Mixed Asian 5 in Mathematics

Determine the number of moles of Krypton contained in a 3.25 liter gas tank at 5.80 atm and 25.5 °C.
If the gas is Oxygen instead of Krypton; will the answer be the same? Why or why not?


I'm pretty sure the equation n=PV/RT should be used in this problem. All the information is given for it except for R, which is a constant, that can change.... confusing.

2007-11-14 17:28:51 · 4 answers · asked by Anonymous in Chemistry

THe value of x in log(subscript 3) 3^(x-2) - log (subscript 2) 32 + log (subscript x) x^2 = 5 is:

A. -4
B. 0
C. 6
D. 8
E. None of these

2007-11-14 17:24:05 · 4 answers · asked by Anonymous in Mathematics

What if scientists discover a life form out in space? However, the life form is humanoid and were 100 times bigger than us humans on earth. Do you think we should try and make contact with this other life form? Wouldn't there be a big chance they would smash us like ants without any interest to learn from us?

2007-11-14 17:19:01 · 8 answers · asked by gemini6187 2 in Astronomy & Space

I need the steps and the answer

2007-11-14 17:15:19 · 3 answers · asked by Kainon 1 in Mathematics

A company must manufacture a closed rectangular box with a square base. The volume must be 980 cubic inches. The top and the bottom squares are made of a material that costs 8 dollars per square inch. The vertical sides are made of a different material that costs 5 dollars per sqare inch.
What is the minimal cost of a box of this type?

2007-11-14 17:12:31 · 1 answers · asked by Anonymous in Mathematics

Can sublimination be used in the project to isolate a particular soil compound?

While the soil compound possibly contains CuCl2, CoSO4, NiCl2 Biphenyl, Benzoic acid, Camphor , m-Nitroaniline and Napthalene.

How does the boiling point and the melting point of these compound tells you rather sublimination can be use or not?

2007-11-14 17:10:08 · 1 answers · asked by Anonymous in Chemistry

The function f(x)= 2 / (Ln(X) - 9) has
a horizontal asymptote y= ,
and a vertical asymptote x= .

2007-11-14 17:08:00 · 2 answers · asked by Anonymous in Mathematics

I'm thinking of studying Geology at University , and wanted to know how demanding it is to study?

will i be able to hold down a part time job without any major interference to my studies?

I didn't take chemistry in my last senior year (year 12 in Australia) , although i did take it in year 11 and have some knowledge.

i also haven't done physics at a senior level

will i be able to cope ??

2007-11-14 17:06:20 · 4 answers · asked by give me TRUTH 3 in Earth Sciences & Geology

2007-11-14 17:04:15 · 4 answers · asked by Anonymous in Paranormal Phenomena

and then divide it in half with a fence down the middle parallel to one side. What is the shortest length of fence that the rancher can use?

2007-11-14 17:02:41 · 4 answers · asked by Anonymous in Mathematics

2007-11-14 17:02:05 · 2 answers · asked by Tonie M 1 in Botany

My equation came out to be

Y=22x-120....and it was not correct....what did I do wrong?

2007-11-14 16:58:35 · 5 answers · asked by RedSparkle 1 in Mathematics

if converting from grams to moles 5 grams of ( 4 C3 H5 N3 O9) (4 being the co-efficent) what are the moles. I forgot how to do simple stuff when you multiply 5(1 mol / molecular mass) do you multiply it by 4? in other words do you do 5(1 mol/ 227.1) or 5(1 mol/908.4) , because of the coefficent. Please i need an answer asap. this is a small step in a half hour problem that goes a long way. Seem to have forgotten my basics.

2007-11-14 16:58:17 · 4 answers · asked by Protons 2 in Chemistry

the number of yards a NFL running back runs in a game has a mean of 80 yards with a standard deviation of 20 yards. a random sample of 5 running backs is selected and we are interested in xbar; the average yards run by the sample.

1. what is the probability that the average number of yards is above 100 yards? draw the graph related to the situation and shade in the appropriate area.

2. find the 85th percentile for the average number of yards.

4. the middle 95% of the average number of yards would fall between what values? "blank and "blank"

2007-11-14 16:57:59 · 2 answers · asked by liuj71 2 in Mathematics

I need to make a bath of it and am rusty on my chemistry.

2007-11-14 16:50:47 · 4 answers · asked by toaddozer 3 in Chemistry

Is it 4x squared or 4x cubed?

2007-11-14 16:46:43 · 18 answers · asked by JESSICA s 1 in Mathematics

Please explain to me in like 3 sentences, I don't get it

2007-11-14 16:41:17 · 9 answers · asked by Anonymous in Botany

Mixtures of helium and oxygen are used in scuba diving tanks to help prevent the bends, which is a condition caused by nitrogen bubbles forming in the bloodstream. If 95 L of oxygen and 25 L of helium at STP are pumped into a scuba tank with a volume of 8.0 L, what is the partial pressure of each gas in the tank and what is the total pressure in the tank at 25°C?

2007-11-14 16:40:32 · 1 answers · asked by sovietwarhawk 1 in Chemistry

Seriously debating about this for a number of days...

2007-11-14 16:39:15 · 7 answers · asked by PoWeR 2 in Zoology

In a study of the properties of an aquoous solution of Th(NO3)4 a freezing point depression of 0.0703K was observed for an aqueous solution of molality 9.6 mmol kg^-1 What is the apparent number of ions per formula unit?

2007-11-14 16:33:51 · 5 answers · asked by ShouldBeSleeping 2 in Chemistry

2x + y = 5
x + y = -2

step by step
solve this

im VERY slow at comprehending

2007-11-14 16:32:30 · 9 answers · asked by hello 2 in Mathematics

can you give me anything concerning about the benefits of using other plants in paper making....tnx

2007-11-14 16:27:27 · 2 answers · asked by Audi 1 in Botany

So far I've split it to ∫(cos x)(1-sin^2 x)^2, and it looked like a simple u substitution, but if you have u=1-sin^2 x, then du=2sinxcosx which doesn't work...so I'm not sure what I'm doing wrong.

2007-11-14 16:26:56 · 3 answers · asked by topher098321 2 in Mathematics

2007-11-14 16:26:41 · 8 answers · asked by Anonymous in Biology

2007-11-14 16:24:40 · 2 answers · asked by 123456789 1 in Biology

Are the chromosones within a cell physically linked to each other by a string of DNA, or are they completely seperate?

2007-11-14 16:21:46 · 11 answers · asked by Chris tf 2 in Biology

information on how to find the vertex form would be more helpful then the actual answer

2007-11-14 16:19:35 · 3 answers · asked by chuck g 1 in Mathematics

solution? Please help

2007-11-14 16:18:29 · 2 answers · asked by Tonie M 1 in Chemistry

like at nite do they see like night vision on a camera

2007-11-14 16:05:49 · 3 answers · asked by berkeleyqueer 2 in Zoology