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Homework Help

For assistance with (but not answers to) homework problems.

Homework Help Rules

A simple reminder to all: this is the "Homework Help" forum, not the "Homework Answers" forum. We will not do your work for you, only point you in the right direction. Posts that do give the answers may be removed.

  1. rule 1) No we will not do your homework for you, the hard work will be good for you and it will turn you into a better person. rule 2) Do not then go on to spam all the other forums with your homework requests, one post here will do, and it will probably get read. rule 3)Not all questions have answers! teachers give questions to make you think, so think. your brain is the result of several million years of evolution, apprecialte it and use it. rule 4) Be Grateful.

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  2. Started by Ice-cream,

    Does any1 know whether ethanol is an water-immiscible organic solvent?

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  3. Guest JassyB
    Started by Guest JassyB,

    I am currently doing a projext on static electricty and I want it to be the best. Does anyone have any suggestions as to which materials are the best for picking up things like human and animal hair?

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  4. Started by Ice-cream,

    with this question, I'm told that i shouldn't be getting any decimal answers becuase the answer is in the number of photons...so can any1 just tell me whether you agree with my answer? A ruby laser produces radiation of wavelength 633nm in pulses of 1.00e-9 s duration. If the laser produces 1.68e-16J of energy per pulse, how many protons are produced in each pulse? i keep getting an answer of 535.46827.... which i think is approx. 535 photons. what do you guys think?

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  5. Started by Kandi,

    Why is ammonia volatile? Also, why is silver nitrate AgNO3 and sodium chloride NaCl non-volatile? I also don't understand the relationship between the volatile nature of a solid and the boiling point elevation? Much appreciated for help

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  6. hey guys, i have 2 questions...hopefully u can help me out! 1. this multiple choice MAY have more than 1 answers...but i only got 1 answer so i just want to know whether u guys think there's only 1 answer as well. Which of the following statements is/are incorrect? (a) The exact momentum and position of an electron cannot be determined. (b) Lower energy orbitals are filled with electrons before higher energy orbitals. © When filling orbitals of equal energy, 2 electrons will occupy the same orbital before filling a new orbital. (d) No two electrons in a particular atom can have the same value for all 4 quantum numbers. (i got © as the incorrect statemen…

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  7. Started by Ice-cream,

    hey can any1 confirm my answer? A hydrogen atom in its ground state absorbs a proton of wavelength 121.5nm. To which higher energy state will it be excited? (a) n=2 (b) n=3 © n=4 (d) n=5 (the answer i got was n = 1.15 so roughly n= 1, using bohr's equation and E = hc/wavelength. but that doesn't match any of the multiple choice answers on the worksheet. wat do u guys think?)

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  8. Started by Sarahisme,

    Hey all, yet another question Suppose an → a, bn → b and an ≤ bn ultimately. Prove that a ≤ b. i am not sure how to do this.... if anyone has some advice or could show me how, it would be greatly appriciated Sarah

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  9. Started by 6431hoho,

    This isn't my homework (except no.3) but I'm wondering... 1. if there was a particle in the EXACT middle of two gigantic stars, then would the particle keep disuniting due to the gravity? 2. What is the name of the theory that states in a long enough period, the axioms/laws of physics will change? 3. In sense of static electricity, what does the wool do to the balloon when rubbed?

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  10. Started by Sarahisme,

    just a quick phys question A wheel mounted on an axis that is not frictionless is initially at rest. A constant external torque of 50 N . m is applied to the wheel for 20 s, giving the wheel an angular velocity of 600 rev/min. The external torque is then re-moved, and the wheel comes to rest 120 s later. Find (a) the moment of inertia of the wheel, and (b) the frictional torque, which is assumed to be constant. and i get (sorry don't have time to write out complete working) a) 60/pi kg.m^2 b) 10 N.m is wrong or right? lol Sarah

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  11. Guest lordSquirrel
    Started by Guest lordSquirrel,

    Hi guys I feel pretty dodgy having my first post in the homework forum, but i've done my share of lurking dammit, i've lurked my little heart out, and now i need some help The question is for a prac in molecular biology. Q1) Imagine that a pair of primers amplify more fragments than the desired one. Which program parameters woudl you modify to suppress this? Would you increase or decrease thier values? I have absolutely no idea. I searched for ages through the textbook and online. I'm assumming prgram parameters that can be increased or decreased are either times or temperatures of the denature, renature and expansion phases? Only information i found w…

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  12. Started by Ice-cream,

    hey guys, i have a few problems which i'm not too sure about...hopefully u guys can help me out! 1. A hydrogen atom in its ground state absorbs a photon of wavelength 121.5nm. To which higher energy state will it be excited? a) n=2 b) n=3 c) n=4 d) n=5 (i used E = hc/wavelength to find te energy, which then i made it equal to deltaE = -2.18 x 10^-18 [1/(n final squared) - 1/(n initial squared)] where n initial is 0 because it is in ground state. The answer i got was n = 1.15...which doesn't match any of the choices...can any1 give me some help?) 2. Which of the following molecules has a nonlinear structure? a) XeF2 b) BeCl2 c) O3 d) CO2 e) N20 (central atom…

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  13. Started by Deified,

    I am doing a paper for bio class on the brains of birde, parrots and crows in particular. I have tried google and google scholar, neither has helped much so far. Does anyone have links related to this subject? I would appreciate any and all. thank you.

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  14. Started by Primarygun,

    In the figure, describe the motion of particles X and Y at the instant. What will be the shape of the string after 1/4 cycle? I don't know which direction that the crests are travelling as there are two sources.

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  15. Started by Primarygun,

    If a wave passed from a shallower region into a deeper region, will its amplitude increase?

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  16. Started by grayfalcon89,

    Here are four questions that I need help on.. I really can't think much.. Thank you very much for your help! 1.What unique ability to bacteria posses in regards to gaining additional DNA? My answer: All cells are clones of each other, and all cells respond to environment in same way. 2. In the lab on simple staining, we pass the slide with bacteria through the fire. What was the purpose of it? My answer: Since we want to observe the bacteria in the stain, we want to do it when it's killed --> and flame kills it. 3. In the lab on simple staining, some of the stain remain on the slide while the slide was rinsed. Why? My answer: Some of the st…

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  17. Started by Sarahisme,

    lol i am having more trouble.... there is always 1 or 2 question i can't do and it drives me nuts!!! well the one this time is.... A function g has the property that lim x→∞ xg(x) = L. Prove that lim x→∞ g(x) = 0. i have never done or been shown how to do a proof like this one and i am compltely lost Sarah

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  18. Started by Sarahisme,

    hey can anyone help me do this problem? Prove using the formal definition of limit lim x→1 √ x = 1 Thanks and cheers Sarah

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    • 2 replies
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  19. Started by Sarahisme,

    hey quick question for part d) of this question..... i am not sure of the answer but i think i know the rest of it...

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  20. Started by Sarahisme,

    hey just a quick question.... if i have to Write down an expression for the x and y components of the gravitational force on an object (1) of mass M1 by an object of mass M2 when object 1 is at a position (x1,y1) and object 2 is at position (x2,y2). is it correct to say

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  21. Started by chari1,

    I have got a Maths project coming up and I would appreciate it if any one could give me some ideas or if possible some links . i was thinkingmaybe doing it on probability of genetics but i cant find info anywhere. genetics. The project has to be 50 pages of booklet and a model if possible,. PLZ HELp

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  22. Started by Sarahisme,

    how do i prove by contradiction that the sum of two irrational numbers is irrational? lol i just can't quite see the trick yet Cheers Sarah

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  23. my problems is i got stuck while i was trying to find the domains of a function, 1) f(x)=(x^3)-(3x^2)+(2x)+5 2) g(x)=(x^2)+5/(x+2) can anyone determine the domain of the two functions? Thanks a lot!

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  24. Started by Sarahisme,

    hey again...got another physics question i need some help with (or help making sure i am actually getting the right answer)..... The light isotope of lithium, 5Li, is unstable and breaks up into a proton (hydrogen nucleus) and an α particle (helium nucleus). In this process, a total of 3.15 x 10-13 J is released, appearing as the kinetic energy of the two reaction products. Determine the velocities of the proton and α particle that arise from the decay of a 5Li nucleus at rest. ( Note: The masses of the proton and alpha particle are mp = 1.56 x 10-27 kg and mα = 4mp = 6.68 x 10-27 kg.) i am working on it now, but i thought i'd give peoples the heads up first…

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  25. Guest magicpie32
    Started by Guest magicpie32,

    I am doing some research for the answers of these two phsyiology questions. I am not having much luck. I hope that someone will be able to help me. 1. Nicotine stimulates cholinergic receptors of the autonomic nervous system. Based on this information, how would cigarette smoking affect the cardiovascular system? 2. Tom loves to soak in hot tubs and whirlpools. One day he decides to raise the temperature in his hot tub as high as it will go. After a few minutes in the very warm water, he feels faint, passes out, and nearly drowns. Luckily he is saved by an observant bystander. Explain what happened THANKS

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