Questions Asked on
February 14, 2015

  1. Chemistry

    1.2048g sample of impure Na2CO3 is dissolved and allowed to react with a solution of CaCl2 resulting CaCO3 after precipitation, filtaration and drying was found to weight 1.0362g. calculate the percentage purity of Na2CO3

    asked by Ana
  2. chem uni

    Insert correct coefficients it is a redox reaction Al2+MnO2=Al2O3+Mn

    asked by CAMELA
  3. Calculus

    a certain radioactive substance is decaying so that at time t, measured in years, the amount of the substance, in grams, is given by the function f(t)=3e^-3t. What is the rate of decay of the substance after half a year: I first found the derivative of

    asked by Sara
  4. Maths Dividing Farction

    I need help to solve this:= 16 pies were shared among some women in a party. Each woman received 2/5 of a pie. How many women were there in the group?

    asked by Sarah JJ
  5. Physics

    How does the energy stored in a capacitor change if (a) the potential difference is doubled, and (b) the charge on each plate is doubled, as the capacitor remains connected to a battery?

    asked by Anonymous

    balance the redox reaction NO2^- + Ag^+ = NO3^- + Ag

    asked by LOLA
  7. Earth Science

    15. _______ currents assist in the transfer of thermal energy from warmer climates to cooler climates. A. Platonic B. Plutonium C. Convection D. Tectonic C? Please explain

    asked by Sarah
  8. physics

    Because a concave lens cannot form a real image of a real object, it is difficult to measure its focal length precisely. One method uses a second, convex, lens to produce a virtual object for the concave lens. Under the proper conditions, the concave lens

    asked by Ted
  9. Physics

    A particle moving along the x-axis has its velocity described by the function v =2t squared m/s, where t is in s. Its initial position is x = 2.8m at t = 0 s. At 2.7s , what is the particle's position?

    asked by Joan
  10. chemistry

    Ethylene gas (C2H2) can be formed from the reaction of calcium carbide (CaC2) with water. What is the reaction rate if 14.2 grams of ethylene gas are produced over 4.00 seconds? The units are mol/s.

    asked by danny
  11. Chemistry

    6 mol sample of Cu2S is roasted in excess O2 to yield Cu metal and SO2. Calculate the mass of Cu metal produced

    asked by Ana
  12. chemistry

    Radioactive waste is difficult to dispose of due to the long time periods needed before the radiation effectively disappears. The US protocol is to store the waste for 10 half-lives of the material after which the waste is no longer considered radioactive.

    asked by danny
  13. chemistry

    The activation energy of a reaction is typically determined by calculating the rate constant for the reaction at two temperatures and then manipulating the Arrhenius equation. If you determine the reaction rate constants for a particular reaction to be

    asked by danny
  14. Anthropology

    First describe how colonization and globalization have affected sociopolitical systems, and then discuss how political systems change. Give examples for each objective

    asked by Casey
  15. philosophy

    This is a prompt that I have to write a 600-900 word response on. I have some ideas of what to talk about/address in regards to the prompt below such as answering if I believe in a supreme Being, then talking about how going to church has influenced my

    asked by Tay Tay
  16. Physics

    An airplane is travelling from Vancouver to Toronto following the jet stream. The plane cruised at an average speed of 1100 km/h for the 4000 km flight. How long did the flight take? If the plane left Vancouver at 3:00 am EST, what time did it arrive in

    asked by GG
  17. Math

    Hello, I can not solve problem from analytical geometry. If you can help me to find out what is wrong in my procedure and show me a better one I would be really gratefull. There are given 3 points A(2,2,3), B (6,3,0), C(3,-1,-1). On the x ax-axis lies

    asked by Viktória
  18. Math

    Find all solutions for the complex numbers: a) z^4 = 9i -46 b) 8*sqrt3 / z^4 +8 =+i

    asked by Complex number
  19. math

    At Sunny;s Smoothies 2/5 of the smoothies are made with citrus fruit and the rest are made with berries.1/8 of the berry smoothies contain bananas.What fraction of all the smoothies are berry banana?

    asked by shawn
  20. Math

    The dissipation of heat through a composite material of width w centimetres can be modelled by the function f(w)=10/w-0.77ln(w)–3.2 You are required to find the width of material that will prevent any heat dissipation. State what equation you will need

    asked by Sam
  21. Maths Fraction

    Need Help... 3/4 of a cake was shared by a group of children. Mrs.Lim gave each child 1/8 of the cake. How many children were there in the group?

    asked by Sarah JJ
  22. Earth Science

    12. The original location of an earthquake is also known as the A. horizon. B. epicenter. C. hotspot. D. magnitude. B?

    asked by Sarah
  23. physics

    A batted baseball leaves the bat at an angle of 33.0∘ above the horizontal and is caught by an outfielder 380ft from home plate at the same height from which it left the bat. 1. What was the initial speed of the ball? 2. How high does the ball rise above

    asked by chibest
  24. Science

    Science To determine the acceleration of an object moving in a straight line, you must calculate the change in its stored during each unit of A. Velocity. B. Time. C. Motion. ******* D. Deceleration Please help

    asked by BUBBLES
  25. Algebra

    Train A leaves station at 9am traveling east at 85 mph. Train B leaves station at 9:30 am traveling west. Both train are on the same track. At what time will they meet?

    asked by Connor
  26. government

    what court hears specific cases?

    asked by kim
  27. Finance

    You are planning to save for retirement over the next 15 years. To do this, you will invest $1,100 a month in a stock account and $500 a month in a bond account. The return on the stock account is expected to be 7%, and the bond account will pay 4%. When

    asked by Kelsey
  28. Finance

    You just acquired a mortgage in the amount of $249,000 at 6.75% interest, compounded monthly. Equal payments are to be made at the end of each month for 30 years. How much of the first loan payment is interest? (Assume each month is equal to 1/12 of a

    asked by Kelsey
  29. Math

    Train A leaves Tigerville at 9 am traveling east at 85 mph. Train B leaves Liontown at 9:20am travelling west at 60 mph on the exact same tracks. Tigerville and liontown are 154 miles apart. At what time will the trains meet?

    asked by Connor
  30. Finance

    Gene's Art Gallery is notoriously known as a slow-payer. The firm currently needs to borrow $27,500 and only one company will deal with them. The terms of the loan call for daily payments of $100. The first payment is due today. The interest rate is 21.9%,

    asked by Kelsey
  31. Finance

    You have an investment with 10 semi-annual cash flows of $1000. The first payment is 6 months from today. If the EAR is 11% what is the present value of this investment?

    asked by Kelsey
  32. Finance

    If the APR is 7% with monthly compounding, compute the quarterly rate

    asked by Kelsey
  33. French

    Which sentence is correct? 1. J'ai anglais de matin. 2. J'ai anglais à matin.

    asked by Anonymous
  34. Physics

    A car and driver weighing 7740 N passes a sign stating “Bridge Out 27.7 m Ahead.” She slams on the brakes, and the car decelerates at a constant rate of 12.3 m/s^2. The acceleration of gravity is 9.8 m/s^2. What is the magnitude of the work done

    asked by Jess
  35. Physics

    Two objects of same material are travelling near you. Object A is a 1.5 kg mass traveling 13.5 m/s; object B is a 2 kg mass traveling 5 m/s. Which object would make you feel worse if you are hit by it? 1. B 2. A 3. Unable to determine 4. the same

    asked by Kim
  36. math

    A scale drawing of a city has a scale of 3 inches : 400 feet. What is the actual length of each foot in the drawing? Show the work.

    asked by Alyssa
  37. Physics

    If the rifle is stopped by the hunter’s shoulder in a distance of 3.16 cm, what is the magnitude of the average force exerted on the shoulder by the rifle? Answer in units of N. mass of bullet= 0.0137 kg velocity of bullet= 546 m/s to the right mass of

    asked by Anonymous
  38. Chen UNi

    This is another one for inserting coefficients HNO3+H2S=NO+H2O

    asked by CAMELA
  39. chemistry

    How do I find the initial rate of reaction for 4.)? 2NO(g)+Cl2(g) ---> 2NOCl(g) [NO] (mol/L) [Cl2] (mol/L) Initial Rate (mol/L * min) 1.) 0.20 1.) 0.10 1.) 0.63 2.) 0.20 2.) 0.30 2.) 1.92 3.) 0.80 3.) 0.10 3.) 2.58 4.) 0.50 4.) 0.50 4.) ???

    asked by mar
  40. calc

    find this value. tan(arctan(3)) how do ifind arctan 3

    asked by kirsten
  41. Business Law

    Can someone point me in the right direction so I can answer this ? Ezra enters into a written contract to purchase a house and lot from Joanne for $80,000. Before the closing, Ezra sees a better house for $70,000 and notifies Joanne that he has changed his

    asked by Giovanna
  42. chemistry

    A student measured the mass of a solid sample and recorded the mass on his data sheet as 20.587 grams. He recorded his initial volume as 7.9 mL and his final volume as 11.1 mL. Calculate the density of the sample.

    asked by ako
  43. chemistry

    Skim milk has a density of 1.028 g/mL. How many grams are needed to get 0.786L?

    asked by ako
  44. Calculus

    would the derivative of f(x)=(7^x)(x^7) be f'(x)=(7^x ln7) (7x^6)?

    asked by Sara
  45. Algerba

    A newspaper carrier has %5.75 in change. He has ten more quarters than dimes but two times as many nickles as quarters. how many coins of each type does he have?

    asked by Tammy
  46. Earth Science

    16. What type of instrument measures seismic waves? A. Mercalli scale B. Seismic scale C. Seismogram D. Seismometer D?

    asked by Sarah
  47. physics

    Galileo's first telescope used a convex objective lens with a focal length f = 1.65 m and a concave eyepiece. When this telescope is focused on an infinitely distant object, and produces an infinitely distant image, its angular magnification is +3.11. What

    asked by Samantha
  48. English

    I need help finding real life examples of these topics 1. The need to fight discrimination can be done by embracing who you are and refusing to conform to others expectations. 2. The importance of family is strong enough to overcome the temptation to give

    asked by Amy
  49. chemistry

    If the breakdown half-life of a pesticide applied to a farmer’s field is 3.50 days, then what is the rate constant for this reaction? Assume the degradation reaction follows first order kinetics. The units are 1/d.

    asked by danny
  50. chemistry

    In which of the following reactions is ΔE closest in value to ΔH? HNO3(aq) + Na2(CO3)(aq) = NaNO3(aq) + H2O(l) + CO2(g) KClO3(s) = KCl(s) + (3/2)O2(g) HCl(aq) + NaOH(aq) = H2O(l) + NaCl(aq) Na(s) + H2O(l) = NaOH(aq) + (1/2)H2(g)

    asked by danny
  51. Pythagoras

    An aeroplane flies 520 km north 45 degrees west then 387 km east . it is then noted that the plane is due north of its starting point. how far is the plane from its starting point? How do I work it out?

    asked by Difficult
  52. math

    For his next trick, a magician will draw a “royal flush” – 10, Jack, Queen, King and Ace of the same suit – in the exact order without replacement. If there are no magic tricks and just pure randomness, what is the probability that he'll succeed?

    asked by probability
  53. math

    find the dimensions of the subspaces of R^2 spanned by the vectors (1,3), (1,-1)?

    asked by maricel
  54. Calculus

    Can someone please explain how to solve this type of question? Determine the maximum and minimum value of the function f(x)=3x3^x - 1

    asked by Sara
  55. Math

    So far john has run 1/4 of the way to school and walked 3/8 of the way.What fraction of the distance to school does john have left?

    asked by Anonymous
  56. Earth Science

    18. Which of the following is a factor that determines the composition of magma? A. Texture B. Elasticity C. Color D. Viscosity D or B?

    asked by Sarah
  57. math

    A rectangular and two circular cut-outs of metal sheet of negligible thickness are used to make a closed cylinder. The rectangular cut-out ha a height of 18 cm. Each circular cut-out has a radius of 5.2 cm. Calculate in terms of area of π, the surface

    asked by kudu
  58. chemistry

    Suppose 100 moles of a chemical is spilled into a lake. After 15.0 days, the total amount of the chemical in the lake 3.50 moles. Assuming that the reaction followed first order kinetics and no chemical was lost due to advection or volatilization, then

    asked by danny
  59. chemistry

    Based on reaction kinetics, which of the following pairs of reactions and reaction rate equations represent elementary reactions? You may choose more than one reaction. Ti + 2Cl2 = TiCl4 Rate = k[Ti][Cl2] 2SO2 + O2 = 2SO3 Rate = k[O2][SO2]2 Na2S + CuSO4 =

    asked by danny