# Questions Asked onAugust 5, 2007

1. ## linear algebra

Determine whether {v1, v2, v3} is a basis for R3 v1 =  [-3]  v2 = [-3]   v3 =  [-2]  Put the vectors as rows or columns in a matrix and perform Gaussian reduction to determne the row or column rank. In this case you should find that the

2. ## Inorganic Chemistry

Which aqeuous solution has a freezing point closest to that of 0.30M C12H22O11? A) 0.075M AlCl3 B) 0.15M CuCl2 C) 0.30M NaCl D) 0.60M C6H12O6 I know the answer but I don't know the reason or rationale behind it. Please explain. I suggest you review

3. ## science

why does methylated spirits evaporate faster than water? less surface tension - water has one of the most abnormally high levels of surface tension For a general explanation on what determines vaopr pressure, see

4. ## Biology

http://talk.collegeconfidential.com/showthread.php?p=4515174 Imagine you had made an RNA copy of each strand of a DNA double helix. If you were now to mix these two RNA single-strand copies together, do you think they would form a double-stranded RNA

5. ## english

What if anything, is wrong with the following sentence? The new drug proved to be highly effective, it has no side effect. a. Comma splice b. Properly constructed sentence. c. Lacks parallel parts d. Has unclear pronoun This is an example of a comma

6. ## physics

A resistor (R = 900 ), a capacitor (C = 0.25 µF), and an inductor (L = 2.0 H) are connected in series across a 240 Hz AC source for which Vmax = 140 V. Calculate values for the following. ---I only need help with part c---- c) the phase angle between the

7. ## physics

Determine the fraction of the energy radiated by the sun in the visible region of the spectrum (350 nm to 700 nm). (Assume the sun's surface temperature is 5800 K.) any help is always appreciated thanks Solve by integrating the 5800 K blackbody function

8. ## chemistry

The basicity constant of pyridine can be expressed as pKb = 8.75 what will be the pH of a 1M (1 mole per liter) solution of pyridine in water? Py + HOH ==> PyH^+ + OH^- Kb = (PyH^+)(OH^-)/(Py) Change pKb to Kb, plug in x for (PyH^+) and (OH^-) and 1 for

9. ## physics

hi can i really get some help on this one. Thankssssss. When electrons pass through a single slit, they form a diffraction pattern. The central bright fringe extends to either side of the midpoint, according to an angle è given by sin =ë/W, where ë is

10. ## statistics

If Z is a standard normal variable, find the probability that Z lies between -1.10 and -0.36 Use the table of the area under the normal distribution in the back of your statistics textbook to find the area between these Z values and the mean. Since they

11. ## Chemistry - Kc question

What would happen to Kc values in an experiment if the Beer's law constance (k) value used was low ( e.g you used 4000/M when the actual constant had a value of 5000/M)? Explain your answer Absorbance = k*length cell*concentration Cell length is constant.

12. ## chemistry - titration

Show that for the titration of a weak acid, HA, with NaOH solution, at half-titer, pH = pKa. Please explain your answer. Thank you. HA + NaOH ==> NaA + HOH Ka for HA = (H^+)(A^-)/(HA) and solve for H^+. (H^+) = Ka*[(HA)/(A^-) When HA is half neutralized,

13. ## calculus

We are not going to do that work for you, but will be glad to help you. The unit sphere is the sphere with radius 1 centered in the origin. They give you the coordinates of a vector. Compute the dot product of the vector and the local surface area normal

14. ## math

1. Define what is meant by the limit of a series. Please try to explain in words more than symbols. The limit is the result you would get by adding up an infinite number of terms of the series. The larger the number of terms that you add, the closer you

15. ## math

Direct variation An airplane is traveling at a constant rate of 450 mi/h. Write an equation that shows how far the plane travels (D) in h hours. D = V * h = 450 h V is the speed, 450 miles/hour

16. ## math

Rewrite the equation 4x – 6y = –30 as a function of x. Subtract 4x from both sides of the equation. Then divide both sides by -6. You should end up with an equation for y, as a function of x.

17. ## physics

a.)At rest, a car's horn sounds at a frequency of 410 Hz. The horn is sounded while the car is moving down the street. A bicyclist moving in the same direction with one-third the car's speed hears a frequency of 381 Hz. What is the speed of the car? b.)Is

18. ## chemistry

10.0 moles of NH3 and 10.0 moles of H2 are introduced into a 1.00 L flask. At equilibrium, 3.0 moles of NH3 gas remain. Calculate Kc for this reaction. N2(g) + 3H2(g) < > 2NH3(g) sorry i forgot to say show all the work please! We usually don't do the whole

19. ## chemistry

There are three xylenes. Their melting points are 13 degrees C, -24 degrees C, and -48 degrees C. Nitration of the isomer with the 13 degree C mp results in only one mononitrated product. The isomer with mp= -24 degree C gives two mononitrated products,

20. ## chemistry

Ethyl acetoacetate is a liquid. The value of the tautomeric constant for neat ethyl acetoacetate is Kt = .079. What is the percentage of the enol form in neat ethyl acetoacetate? please show all the work thanks!

21. ## science

Of all possible DNA nucleotide sequences, what sequence of base pairs would dissociate most easily into single strands if the DNA duplex were heated gently?

22. ## computer science

Here is a question which for some reason I feel very unsure with. Can you guys take a look and see if you agree or disagree with what I have? I personally think that the below situation is safe and secure: Your software company has produced the following

23. ## computer science

Hi, I have this quick question: A Java interface can be used almost anywhere a class can be. Describe the one place/situation where it cannot be used in a place of a class name. Thanks a lot. Not sure what you mean by "in a place of a class name."

24. ## physics

An electron of kinetic energy 41 keV moves in a circular orbit perpendicular to a magnetic field of 0.330 T. (a) Compute the radius of the orbit. The answer to this part is 2.07mm. (b) Find the frequency of the motion. I'm not sure how to find the answer

25. ## physics

What is the minumum potential that must be applied across an x-ray tube in order to observe each of the following? What is the min of the continuous spectrum in each case? (a) K line of potassium ____kV ____nm (b) K line of tin ____kV ____nm (c) L line of

26. ## physics - quantum mechanics

hi can you please help me with this particular question? thanks a lot ___________________________________ The work function of a material refers to the minimum energy required to remove an electron from the material. Assume that the work function of gold

27. ## nuclear chem

i need help solving this. Can you guys show me how it's done. Radium-226 decays by alpha emission to radon-222, a noble gas.What volume of pure Radon- 222 at 23oC and 785mmHg could be obtained from 543.0 mg of radium bromide,RaBr2 in a period of 20.2

28. ## Chemistry, #7

The pH of a 1.00 x 10^-3 M solution of pyrrolidine is 10.82. Calculate Kb. I know pyrrolidine is acidic because of the pH, and I know that tells me something about the Ka which in turn tells me something about the Kb. What does it tell me? Where should I

29. ## ecoc

i can not figure this out the economist for the grand corporation has estimated the company's cost function, using time series data, to be TC=50+16Q-2Q2+0.2Q3 a.plot this curve for quantites 1 to 10 b.calculate the average total cost,average variable cost,

30. ## physics

hi can somebody help me with this?? a solenoid of length L and radius R carries a current I in its N turns. what is the total energy stored in the magnetic field within the solenoid? Compute the inductance L using the solenoid formula. You should be able

31. ## math-differential equations

hi i need to know how to do this one thanks Find the solution to yx + x + (dy/dx) = 0 ; y(9) = -9 y = ???? Does this separate the variables? dy/dx=-x(y+1) dy/(y+1) = -x dx

32. ## Algebra II

Factor out: 1-125b^3 5b -1 is one of the factors. (Consider that an informed guess). Divide that into 1-125b^3 for the other (binomial) factor.

33. ## physics- electrodynamics

can someone walk me through this --- you'd be a lifesaver a rectangular pipe running parallel to the z axis(-‡ to +‡) has 3 grounded metal sides at y=0, y=a and x=0. the fourth side at x=b is maintained at a specified potential v0(y). a. Develop a

34. ## math

help on this one would be appreciated Find the area of only the area which contains both the circles r=4cosƒÆ and r=4ã3sinƒÆ

35. ## Chemistry

Calculate the hydronium ion concentration in 50.0 mL of 0.10M NaH2AsO4. and we are given K1 = 6.0E-3, K2 = 1.1E-7 and K3 = 3.0E-12 I assumed these K values where given in respect to the Ka of acid H3AsO4. (H^+) = sqrt[(k2(H2AsO4^-2)+Kw)/1+(H2AsO4^-2/k1)] I

36. ## Organic Chemistry

Why does CH3Br react faster with hydroxyl ions (OH^-) than CH3Cl? In the halogen series, Br has a weaker bond with the CH3 than Cl. Smaller halogen atoms have a larger electron affinity to fill the outer shell. The greater tendncey of CH3Br to break up

37. ## statistics

Can someone provide me with some assistance in answering this question.. A company manufacturers batteries in BATCHES of 18 and there is a 3% rate of defect. Find the standard deviation for the number of defects per batch. The probability of a defect is p

38. ## staistics

Can someone assist me in answering this question. Use the given values of n and p to find the mimimum usual value of u-2standard deviations and the maximum ususual values u+20. n-186, p=0.13

39. ## math

Find equations for the asymptotes of the hyperbola x2/9 - y2/81 = 1 Rewrite the equation as (x/3)^2 - (y/9)^2 = 1 When both x and y are very large in absolute value, the "1" on the right is negligible in comparison, so y/9 approaches +/- x/3 The asymptotes

40. ## Algebra

I having a hard time with this word problem: A backyard has dimensions 4 and 2/5 yards by 2 and 4/5 yards. What is the area of the backyard in square yards (yd^2)? Do I mulitiply and then simplify? Yes, you do multiply and then simplify. To make it easier

41. ## Statistics

How much more would you expect to pay for a home that has four bedrooms than for a home that has three bedrooms? Here are some data for West Lafayette, Indiana. These are the selling prices (in dollars) that the owners of the homes are asking: Table 1:

42. ## Statistics

For some reason I didn't get the entire questions submitted on the previous email. I really need help with the last part - the part about the crusty old professor. THANKS. K Students in a very large first year college class at a prestigious college were

43. ## math

What is a better way to remember your timed tables? Is there a game or a song you can go by or something? These websites have games and many ways to practice the times tables. http://www.woodlands-junior.kent.sch.uk/maths/timestable/index.html

44. ## Math/Statistics

does anyone know anyting about standard deviation... I have no idea what it is! http://en.wikipedia.org/wiki/Standard_deviation http://www.robertniles.com/stats/stdev.shtml

45. ## Accounting

Does retained earnings include investment capital? I thought no. I thought retained earnings is cumulative net income - dividends. However, Wikipedia says: Ending Retained Earnings = Beginning Retained Earnings + Investments − Dividends Paid + Net Income

46. ## health and human services

What are some arguments for and against HIPAA? This article details some of the arguments for and against HIPAA. http://en.wikipedia.org/wiki/Health_Insurance_Portability_and_Accountability_Act