Homework Help

The half-life of Na-24 is 15 hours. When there are 1,000 atoms of Na-24 in a sample, a scientist starts a stopwatch. The scientist stops the stopwatch at 45 hours; there are ______ atoms of Na-24 remaining. This is an example problem to the section. I just am unsure of the process. Thanks in advance

Hi all, Im writing a paper discussing the following statement: "All Biomass is sunlight" I was wondering if anyone knew any good websites which includes scientific arguments that contradict this statement as well as those that support it. Any suggestions and help will be appreciated thanks in advance.

Is it possible to make a fourteen point test cross?

In these questions, I don't understand what answer I should put. Can anyone help me? 1) Each pixel that appears in a color picture is a combination of three prime colors. Specify these three colors, each of their bandwidth wave length, and if possible - outline the visible bandwidth. I know the colours (red, green and blue) but I'm not sure what bandwidth wavlength and visible bandwidth means. This is more a photography question so I hope someone can help: 2) Explain how different colors are represented in digital photography

Here's a question I got for homework and I really do not have a clue on how to do it. Even if somebody could do pieces of it, I would be most grateful. A capacitor© of 10 μF is connected in series with a resistance® of 5kΩ across a 20 V d.c supply (E). Calculate (i) The initial charging current. (ii) The initial voltage across the capacitor. (iii) The Time Constant (T) of the circuit. (iv) The voltage and current at the Time Constant. (v) The voltage across the capacitor after 75 milliseconds (vi) The time for the current to reach 2 mA. (vii) The time for the voltage to reach 18 V. (viii) The voltage on the capacitor after a long time period. Note : The char…

i hav a problem... As i understand it, there are 4 fundamental forces. now, these have been given various levels of strength. eg-you could say that gravity is the weakest force. however, when you talk about strength, there just isn't any way to compare their strengths. if we take gravity and electromagnetism, for example, gravity depends on the mass of 2 (say) particles, and electromagnetism would depend on the charge on 2 particles. so how is it possible to compare these forces when you have no possible relation between mass and charge? i mean to say that- since we have not yet found a link between the fundamental forces, we cannot compare them. if x unit charge attrac…

This isnt exactly hw so u can answer it freely, just out of curiosity, more like. well, i've read about parallax and what it is and how we can calculate ditances of far-off bodies with it, i just wished sum1 cud tell me the equations with which u can calculate the distance of the body with it. thx.

why are alpha and beta particles deflected in opposite directions in a magnetic field? and also are x-rays most similar to alpha, beta or gamma rays?

I have a biology reference book stating that "polygenic inheritance is applied when multiple independent of genes have similar and additive effects on the same character. Alleles at several, perhaps many, loci affect each character." What i was wondering is whether these loci controlling a single character are situated at the same chromosome or are they scattered at different chromosomes? Thanks

questions attach thank you xam_a2001.pdf

Hey,I am studying for a science test and I would like a way to study really well and effectivly:-)

My teacher told me to write a report on the Origin of Species by Charles Darwin. I don't know what to do since she didn't exactly mention what she wants to see in our reports. I don't know if she wants our personal insights on it or if she wants a summary of the text. Please please... I need your opinions on what do you think I should submit.

Hi, I'm new to this site but I need a great help on my bio. Question: How many ATP molecules are formed in process of glycolysis itself? How many ATP molecules are formed in the process of respriation? How many ATP molecules are formed in process of glycolysis and fermentation (meaning the combination of those two)? I know for total thing, glycolysis and respiration whole thing will make 36 ATP molecules. But there occur confusion to me on the book. It seems the diagram is saying like 4 ATP are formed on glycolysis but in the paragraphs, it's only 2 ATP on glycolysis. Same thing for respiration. Diagram looks like 32 ATP but 34 ATP on paragraphs. For fermentation …

This may be a simple question, but how does one calculate the melting point of ice at a given pressure when density of ice and water are given and the heat of melting? I also have pressure and temperature of the tripelpoint of water.

So I have an exam coming up and I'm working on the review and I was wondering if you guys could answer a few things. 1) What is the relationship between atoms and ions. 2) What is the relationship between elements in families of the periodic table. 3) What is the relationship between slope and speed. 4) What is the relationship between populations and communities. 5) Compare families and periods on the periodic table. 6) How do you determine the number of atoms in compounds. 7) How do you determine the rate of acceleration. 8) How do you determine the acidity from a pH scale. Any help would be appreciated.

The first two terms of a geometric progression are x and y where -x < y < x (<--what does this mean?) If the sum of the first n terms is equal to the sum to infinity of the remaining termsm prove that x^n = 2y^n. So I did this. T1 = x = a T2= y r= y/x Tn+1 = y^n ... x(1-(y/x)^n) = y^n (after substituting a and r values into G.P formulae) But i don get the answer! what's the prob?

I'm kinda new here so if I did a violation just let me know. My 1st year highschool sister asked me about her assignment in science. 1) What is science? [already answered] 2) How does it start? -That one I don't understand it's pretty hard to search into the internet. I can't get a simple answer, reffering to the education level/standard of a 1st year highschool. I just want a simple and short answer for this, about 3 or 4 sentence I guess.

Design a device that can safely transport an egg when dropped from about 10+ meters to the ground (the egg cannot crack or break.) The device must have a max of 100 grams (record is 17g) and may be made of wood, cloth, plastic, string, paper, glue, metal, tape, rubber and/or cardboard. It cannot be made of anything that will rot or smells, liquids, or gels or anything that could potentially injure someone. The device may not include padding of any kind inside or outside the structure, containers filled with gas (bubble wrap, balloons, etc), a parachute or wing of any type, or wrapping or coating of the egg. Other requirements are a way to easily insert and remove the egg…

Our class was given a "ridiculously hard" extension maths project. I've been able to answer all the questions except one. This is the problem: --------------------- The variable [math]x[/math] is defined: [math]x = 1/2^2 + 1/3^2 + 1/4^2 + 1/5^2 ...[/math] Express the infinite sum [math]1 + 1/2^2 + 1/4^2 + 1/6^2 + 1/8^2 ...[/math] in terms of [math]x[/math]. --------------------- Could someone please give me a clue to solving this? I don't even know where to start. The teacher who wrote the project has received quite a lot of complaints lol.

How can you tell what sort of hybridisation a molecule has?

I have difficulty understanding the concept of "Function" and "Limit of a Function", Please help.

Hello, Im having trouble finding information about lidocaine Im trying to find the : -bond lengths and bond angles between the atoms -The physical / chemical properties of the molecule -intermolecular forces of attraction present that account for these properties could anyone help please...I'd appreciate it..thank you

Hello everyone i have been trying to understand physics for the past week and i haven't been able to get any tutors all of them are booked. so i have my practice test that the teacher has given us and i was wonderin if anyone could help me out. i don't understand any of it and each time i do any of the calculations i second guess my self becasue there are 2 answers to the problem because i don't know which exact equation to use please can someone help me out. i will email them the practice test but please come one help me out i really don't understand this stuff!!!! my email is qcksteel114@yahoo.com please can some one help!!!! -Jack

Ok, ive got this all mixed up If I have 5 concentrations of a substance (IAA) 10-4, 10-3, 10-2, 10-1 and 1, can you please list them from highest to lowest concentration (urgent reply needed). Trust me you will only be steering me in the right direction, this isnt all my homework, I have to write a whole prac report by tomorrow.

Hi all, I'm trying to answer an assignment question that asks me to draw and name the isomers of a particular transition-metal complex and then identify the number of chemically inequivalent telluriuim atoms in the isomers. So far, so good except for I'm a little confused with regards to my nomenclature for the transition-metal complex that I have. It's octahedral and contains only two distinct ligands: in other words, it has two sets of three identical ligands. Thus, it fits nicely with the fac/mer system of naming - I can identify that it can have both facial and meridional isomers. What I'm not sure about is whether I can (and should) apply the Cahn-Ingold-Pre…