# Questions Asked onMay 20, 2007

1. ## Chemistry II

C4H4 (g) + 2 H2 (g) --> C4H8 (g) Combustion reactions involve reacting a substance with oxygen. When compounds containing carbon and hydrogen are combusted, carbon dioxide and water are the products. Using the enthalpies of combustion for C4H4 (-2341

2. ## algebra

If v1,...,v4 are in R^4 and v3 is not a linear combination of v1, v2, v4 then {v1, v2, v3, v4] is linearly independent. Is this true or false? Why? If v1,...,v4 are in R^4 and v3 is not a linear combination of v1, v2, v4 then {v1, v2, v3, v4] is linearly

3. ## Math

How do I solve this problem? There are 8 sections of seats in an auditorium. Each section contains at least 150 seats but not more than 200 seats. Which of the followin could be the number of seats in this auditorium? What are your choices? Multiply 150 x

4. ## Algebra

How many pivot columns must a 5x7 matrix have if its columns span R^5? Why?

5. ## Math

The table shows some values for the function f. If f is a linear function, what is the value of a+b? a24 b36 c48 d72 eit cannot be determined from the information given. x f(x) 0 a 1 24 2 b The Answer is c48. How did they arrive at that answer????????? The

6. ## physics

A student conducted an experiment to determine the resistance of a lightbulb. while performing the experiment the student noticed that the lightbulb began to glow and became brighter as she increased the voltage. of the factors affecting resistance, which

7. ## Math

I don't understand this!!! If rstv=1 and stuv=0, which of the followin must be true? a.r

8. ## English

Does anybody know any websites that will give me information on the benefits and salaries that a store manager and a hand model( jewelry and perfume) earns http://www.payscale.com/research/US/Job=Retail_Store_Manager/Salary I could find no information on

9. ## Chemistry II

The enthalpy of neutralizatino for the reaction of a strong acid with a strong base is -56 kJ/mol of water produced. How much energy will be released when 230.0 mL of 0.400 M HCl is mixedwith 150.5 mL of 0.500 M NaOH? How much water is produced in the

10. ## Chemistry II

The enthalpy of neutralizatino for the reaction of a strong acid with a strong base is -56 kJ/mol of water produced. How much energy will be released when 230.0 mL of 0.400 M HCl is mixedwith 150.5 mL of 0.500 M NaOH? How do I figure out how much water is

11. ## Chemistry

Hydrogen iodine is a strong acid that is used in chemical synthesis to produce some common drugs as well as a source for iodine, I2. Data for the formation of hydrogen iodine was obtained as shown. The reaction was found to be first order with respect to

12. ## cells

what are the properties of blood cells. Since this is not my area of expertise, I searched Google under the key words "blood cells" to get these possible sources: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/B/Blood.html

13. ## equations of tangents and normals

hi, i'd really appreciate some help solving this question! I am completely at loss here :/ The question is to: Find the equation of the normal to y=loge(x+2) which is parallel to the line with equation y+3x-5=0 I am fine at solving these sorts of equations

15. ## maths

the function y = 5 + 3 sin (pie t /3 + pie /2) choose one option which gives the value of the funtion when t = 3. choose the option which gives the period of the function. from the options below. 0, 1/6, pie/6, 2, 3, pie, 5, 6 wod the value of t=3 be 5 ?

16. ## Algebra

Write the equation of the line passing through the given point with the indicated slope. Give your results in slope-intercept form. Point: (0,5) Slope: m=-3/5 Show equation I will be happy to critique your work on this.

17. ## Algebra

Write the equation of the line passing through the given pair of points. Write your result in slope-intercept form. (-1,3) and (4,-2) Show equation I will be happy to critique your work on this. y-3=1(x+1) y-3=1x+-1 y=x+2?

18. ## Algebra

Write the equation of the line passing through the given pair of points. (2,-3) and (2,4) I will be happy to critique your work on this.

19. ## Algebra

Write the equation of the line L satisfying the given geometric conditions. L has y-intercept (0,2) and is perpendicular to the line with equation 2x-3y=6 Show work I will be happy to critique your work on this. 3x+2y=4?

20. ## Algebra

Write the equation of the line L satisfying the given geometric conditions. L has y-intercept (0,-3) and is parallel to the line with equation y=2/3x+1 I will be happy to critique your work on this. y=(2/3)x-3?

21. ## Algebra

In planning for a new item, a manufacturer assumes that the number of items produced x and the cost in dollars C of producing these items are related by a linear equation. Projections are that 100 items will cost \$10,000 to produce and that 300 items will

22. ## maths

Choose three options which are true: a) an angle of 150 degrees is equivalent to 2pie/3 radians. b) Cos 0 = cos (0 – pie/2) for al values of 0. c) Sin 0 = cos (0 – pie/2) for all values of 0. d) If triangle ABC has a right angle at B, then sin A = cos

23. ## Matrh

How do you solve this problem? The avera&e (aritmeticmean)of x and y is 5 and the avera&e of x, y, and z is 8. What is the value of z? (a)19 (b)14 (c)13 (d)11 (e)3 I solved it by addin 8+5=13 So I chose (c)13. But it's wron& and the answer is (b)14. How

24. ## Chemistry

Our teacher asked, a few weeks ago, for us to find the pH of 7.65 E-11 M HClO3. We were told that we couldn't find the pH simply by -log[7.65E-11]. He said that we had to account for the water somehow [I think we had to do something with the number 1.0

25. ## Math

If 4 less than 3 times a certain number is 2 more than the number ,what is the number? a.-1 b.-3 c.1 d.2 e.3 Do I solve it like this: 3n-4=n+2?? If so, how do I solve this problem? You have the equation right.

26. ## acid base chem

I'm reviewing my notes for a test tomorrow, and I found that I have a question concerning acids that under go multiple protonizations. I know the molarity [or moles, if that's being calculated] of H3O+ of the first protonization can be found using the Ka,

27. ## physics

how can i calculate the slope of the best-fit line in a length v.s. resistance(x=length;y=resistance) graph where the plotted points are: (5.1,1.6)(11.0,3.8)(16.0,4.5)(18.0,5.9)(23.0,7.5)? Personally, I would graph the points, and draw a best fit line,

28. ## alg.

solve and graph 2x-y=4 2x-y=6 would this be x=2+0.5y x=3+0.5y and then graph as that??????? not really sure what i am doing here Put both equations in the form of y=mx +b Then observe that the slope is the same, the lines are parallel, and have no common

29. ## Science

How do clouds form, and where in canada would you expect to see certain types of clouds. What is the difference between clouds and fog? http://en.wikipedia.org/wiki/Cloud

30. ## english

for english i have to do a project and it can be on anything i want. i have to have a persuasive essay and a how to and the history on the subject. like my friend is doing ice cream and we are making it in class. my other friend is doing texting and having

31. ## Chemistry II

The total volume of hydrogen gas needed to fill the Hidenbrug was 2.0e8 L at 1.0 atm and 25 degrees Celsius. How much heat was evolved when the Hidenburg exploded, assuming all the hydrogen reacted?

32. ## calc 2

given x=2cos(t)+t*sin(t) and y=2sin(t)-t*cost(t), with t:[pi, 2pi] find all critical values. by finding dy/dx and setting it equal to zero, i only find one value, t=6.121, within that domain. that gives you x=.987. I'm suppose to get three other answers.

33. ## maths

For the formula Y = AX + B to make X the subject wod it be X = AY – B ?? no ax+b=y subtract b from both sides, then divide both sides by a.

34. ## Chemistry II

Calculate the change in heat: 2 Na(s) + 2 H2O(l) > 2 NaOH(aq) + H2(g) So far this is what I have: 2 H20 --> 2 H2 + O2 2(285.83) kJ 2 Na + O2 + H2 --> 2 NaOH 2(-426.73) kJ 2 Na + 2 H2O --> 2 NaOH + H2 -281.8 kJ If this correct?? yes, correct, as best as I

35. ## Chemistry II

The total volume of hydrogen gas needed to fill the Hidenbrug was 2.0e8 L at 1.0 atm and 25 degrees Celsius. How much heat was evolved when the Hidenburg exploded, assuming all the hydrogen reacted? I will be happy to critique your thinking on this. First,

36. ## Math

3,5,-5... The first term in the sequence of #'s shown above is 3. Each even # term is 2 more than the previous term and each odd # term, after the first, is -1 times the previous term. For example, the second term is 3+2, and the third term is (-1)x5. What

37. ## science

what steps can be taken by rwanda to reduce degradetion and deforestation (Broken Link Removed) I don't know what you mean by degradetion, but deforestation, the way to reduce it is to control the forests: who is there, who does what, and when. I frankly

38. ## Chemistry II

The total volume of hydrogen gas needed to fill the Hidenbrug was 2.0e8 L at 1.0 atm and 25 degrees Celsius. How much heat was evolved when the Hidenburg exploded, assuming all the hydrogen reacted? 2.0e8 L H2/22.4 L H2 = 8.9e6 mol H2 For every 2 mol H2

39. ## ethics

write a memo explaining how you would enhance communication during a business trip to another country. We'll be glad to critique your memo. Thank you for using the Jiskha Homework Help Forum. Since you say a "memo" you might like the following site from

40. ## language

I need to write a paragraph describing my utopian community. What is your ideal community? If you post your paragraph, we'll be glad to comment on it. Thank you for using the Jiskha Homework Help Forum. You only have to write ONE paragraph? Here's how to

41. ## Pre-Calculus

How can the following two identities be verified? 1. (cos^2y)/(1-siny)=1+siny 2. sin^2a-sin^4a=cos^2a-cos^4a Thanks! change cos^2a to 1-sin^2a=(1-sina)(1+sina) Thank you. I figured out the first one with your help, but I'm still stuck on the second. Any

42. ## algebra

1. (3-sqrt6)/(5-2sqrt6) 2. (2sqrt3-sqrt6)/(5sqrt3+2sqrt6) Don't you do something with the conjugate or something like that? 3-sqrt6 5+2sqrt6 --------- x -------- 5-2sqrt6 5+2sqrt6 yes, exactly. Multiply out the numerator, and in the demoninator you will

43. ## Chemistry

How does one calculate the pH of a solution that is only 1.84% ionised? determine the concentration of the H+, which will be in a monoprotic acid, concentration * decimal percent. then determing pH in the normal way.

44. ## chemistry

Does anyone know what advantage there is to using hot water to make ice cubes? Validated tests indicate it is faster to freeze because it has less dissoved air, some of it evaporates, and that evaporation cools it rapidly, and in the end, because some of

45. ## Chemistry II

I will be happy to critique your thinking on this. First, calculate the moles of H2 used. 2.0e8 L H2/22.4 L H2 = 8.9e6 mol H2 For every 2 mol H2 used -572 kJ of energy is produced -572 kJ/2 mol H2 = -2.86e2 kJ/mol I have a balanced equation with this

46. ## Chemistry

If the hydrochloric acid is warm, is the following equation correct? 2HCl(aq) + Na2SO3 --> 2NaCl(aq) + SO2(g) + H2O(l) yes, correct.

47. ## Math

Solve the system by graphing by any method of your choice. 3x-y=1 or y=3x-1 3x-y=2 y=3x-2 (0,-1),(2, 5)and(0,-2),(-2,4) Solution is Consistent, lines intersect at (-1/4, -5/4). Above is my answer but I keep coming back to this again and again. Am I missing

how do you multiply a radical with a regular number ? for example: 4radical2 ( 2+ 2radical3) first term: 4sqrt2 * 2= 8sqrt2 second term 2sqrt2 * 2 sqrt3= 2*2 * sqrt (2*3) = 4 sqrt6 first term: 4sqrt2 * 2= 8sqrt2 second term 2sqrt2 * 2 sqrt3= 2*2 * sqrt

49. ## science

Identify 2 everyday things affected by change in altitude. One I have as airplanes. boiling temperature of water. air pressure The type of plant growth would be another factor. Since the animal life depends on the plants, animals present at various

given x=2cos(t)+t*sin(t) and y=2sin(t)-t*cost(t), with t:[pi, 2pi] find all critical values. (4 answers)

51. ## Algebra

Find the GCF for each of the following groups of numbers. 36, 54, and 180 Find the LCM for each of the following groups of numbers. Use whichever method you wish. 8, 15, and 20 can anyone IM me or email how to SIMJPLIFY RADICAL EXPRESSIONS please?

52. ## MATH

I am having lots of trouble with SIMPLFYIGN RADICAL EXPRESSIONS can anyone help>? Please

53. ## Calculus

I don't understand what the graph is suppose to show and what the integral equation is suppose to mean. How would I use the graph to answer the questions? f is the differentiable function whose graph is shown in the figure. The position at time t (sec) of

54. ## socila studies^-^ ! help

name at lease 5 important event that took place in the history of texas.(NOTE: historical events are important things that happened in the past.do not put annual events here.) http://en.wikipedia.org/wiki/History_of_Texas a major confederate blunder which

Could someone show me how to solve these problems step by step.... I am confused on how to fully break this down to simpliest terms sqrt 3 * sqrt 15= sqrt 6 * sqrt 8 = sqrt 20 * sqrt 5 = since both terms are sqrt , you can combine them. sqrt 3* sqrt 15=

56. ## World History

Hi, I am preparing a presentation on Argentina- 20th century history which covers the country economically, socially and politically. Are there any websites that may help me with the social history of Argentina during the 20th century? Thanks

57. ## algebra

can anyone tell me about polynomials please You need to be more specific in your question. Polynomials is just about half of a beginning algebra course.

58. ## english

I find it at http://en.wikipedia.org/wiki/Cagoule There is a relationship -- what the people referred to in the second link wore -- a cowl ( http://www.answers.com/cowl ). I think the origin is French, but I can't find anything specific either. =( Thanks

59. ## parabolas

how do i find the equaion of the following parabolas? 1)intercepts at (2,0),(8,0) and (0,48) 2)turning point at (1,-2) and passing through the origin. can someone please teach me how to do this??thanks! The first: Write you standard equation of a parabola

60. ## SCIENCE HELP

Can anyone anyone please help me or guide me to a web site where I can find this information? Thank you. Dolphin and porpoise populations are endangered by the _________ fishery. I have twenty questions to complete on my paper and I found all the answers

61. ## Math

Solve the system by addition or substitution. 3x – 4y = 8 6x – 2y = 10 Please get me on the correct track for 3x -4y =8 x=4, y=1 for 6x - 2y =10 x= 2, y= 1 Solve one equation for x. 3x = 4y + 8 x = (4y + 8)/3 Insert that value for x in the other

62. ## Physics

Any help pleeeze!! I'm totally lost on these!! 1. A 14 g coin slides upward on a surface that is inclined at an angle of 16° above the horizontal. The coefficient of kinetic friction between the coin and the surface is 0.23; the coefficient of static

63. ## Bio...DNA

Can anyone explain the relationship between the structure of DNA , protein structure and phenotype of an organism? Also, what is the role of DNA in protein synthesis? I will give you a little hint. The DNA makes the RNA. The RNA makes the proteins by amino

64. ## chemistry

What is the acid and base whose reaction will produce the salt Na3PO4? What is the acid and base whose reaction will produce the salt PbS? What is the acid and base whose reaction will produce the salt KIO3? phosphoric acid, sodum hydroxide lead hydroxide,

65. ## maths

How to calculate the mean number of threatened fishes, where total number of fishes is 29300 and number of threatened fishes is 1173. Hmmmm. you have one data point, that is, 1173 fish are threatened. The mean of one number is that number. Is there

66. ## Algebra

Find the slope of any line perpendicular to the line through the points (0, 5) and (-3, -4). Show work Find the slope of the line through the two points: slope= (y2-y1)/(x2-x1) you do that. Now the slope of the line perpendicular to this is the negative

67. ## Algebra

Write the equation of the line passing through the given point with the indicated slope. Give your results in slope-intercept form. Point: (0,5) Slope:m=3/5. Show work Well, youknow the form is y= mx+b you are given m. You are given a point (0,5) Put that

68. ## BiO

I am comfused about meiosis and mitosis. First of all, both are forms of asexual reproduction, right? I know that in mitosis, you end up with two offspring. In meiosis, you end up with four. I don't get the part about the chromosomes. If you start out with

69. ## Chemistry

The enthalpy of solution of CaCl2 is -82.88kJ. If the specific heat of the solution is 4.184J/g*C and the calorimeter constant can be neglected, what will be the final temperature after 5.36g of CaCl2 is dissolved in 100.0g of H2O at 25.0C? I assume the

70. ## Algebra

Find the slope of the line through the following pairs of points. (4,3) and (-5,3) equals to 0 Notice the y is constant, this is a horizontal line, zero slope.