Most popular questions and responses by victor
  1. More Chem

    Consider the combustion of propane. Delta H is -2221 kJ. Assume all heat is from combustion of propane. What mass of propane must be burned in order to furnish this amount of energy assuming the heat transfer process is 60% efficient.

    asked on April 8, 2017
  2. Chemistry

    Label each of the following reactions as exothermic or endothermic ("exo" or "endo"), and according to whether work is done on or by the system, or no work is done at all ("on", "by" or "none")? Note that no "endo-on" cases appear here, as these are always

    asked on November 22, 2009
  3. Chem

    A 30 g sample of water at 280 K is mixed with 50 g of water at 330 K. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.

    asked on April 8, 2017

    How many liters of chlorine gas at 25C and 0.950 atm can be produced by the reaction of 24.0 g of MnO2 with hydrochloric acid? The products include manganese (II) Chloride, water, and chlorine.

    asked on April 8, 2017
  5. Physics

    Archimedes purportedly used his principle to verify that the king's crown was pure gold, by weighing the crown while it was submerged in water. Suppose the crown's actual weight was 14.0 N. The densities of gold, silver, and water are 19.3 g/cm^3, 10.5

    asked on December 3, 2012

    What is the potential energy of a 150 kg diver standing on a diving board that is 10 m high?

    asked on April 24, 2016
  7. science

    (Points: 10) For the following: i) HClO4 > HBrO4 > HIO4 ii) NH3 > PH3 > AsH3 > SbH3 iii) HOClO3 > HOClO2 > HOClO > HOCl iv) HBr>HCl>HF The order of acidity is correct for which series? 1. ) all are correct 2. ) ii and iii 3. ) ii and iv 4. ) ii 5. ) i,

    asked on November 21, 2009
  8. physics

    A child bounces a 54 g superball on the side- walk. The velocity change of the superball is from 23 m/s downward to 19 m/s upward. If the contact time with the sidewalk is 1 800 s, what is the magnitude of the average force exerted on the superball by the

    asked on November 15, 2012
  9. Physics

    A person takes about 20 breaths per minute with 0.5 litre of air in each breath. How much heat is removed per hour by the moisture in the exhaled breath if the incoming air is dry and the exhaled breath is fully saturated? Assume that the water vapour

    asked on May 21, 2010
  10. science

    (Points: 10) For the following: i) HClO4 > HBrO4 > HIO4 ii) NH3 > PH3 > AsH3 > SbH3 iii) HOClO3 > HOClO2 > HOClO > HOCl iv) HBr>HCl>HF The order of acidity is correct for which series? 1. ) all are correct 2. ) ii and iii 3. ) ii and iv 4. ) ii 5. ) i,

    asked on November 22, 2009
  11. physics

    You are given a vector in the xy plane that has a magnitude of 94.0 units and a y component of -44.0 units. A. What are the two possibilities for its component? For this part I got x = 83.1 and -83.1 B. Assuming the x component is known to be positive,

    asked on July 21, 2011
  12. physics

    A space vehicle accelerates uniformly from 50m/s at t=0 to 182m/s at t=1 0.0s. How far did it move between t=2.0s and t=6.0s?

    asked on July 10, 2011
  13. kelvin

    P,Q and R are points on the same horizontal plane .the bearing of Q from P is 150° and the bearing of R from Q is 060°. if |PQ| =5m and |QR|=3m find the bearing of R from P correct your answer to the nearest degree

    asked on January 9, 2017
  14. Math

    The shipping clerk packs a cube with side lengths of 8 inches into a box with side lengths of 10 inches. What is the volume of the space left in the larger box for packing materials?

    asked on February 15, 2017
  15. geometry

    an equilateral triangle of side 20cm is inscribed in a circle.calculate the distance of a side of the triangle from th centre of the circle.

    asked on March 30, 2011
  16. Maths

    A sector of a circle of radius 7cm subtending an angle of 270 degree at centre of the circle is use to form a cone? (A)find the base radius of the cone. (B)calculate the area of the base of the cone.

    asked on February 2, 2016
  17. Physics

    There is a charge that is 1uC and another charge that is 2 uC. They are 10 cm apart. I need to find a point where the electric field is zero. All I have is this kq1\a=kq2\(10-a)^2 where q1=1 where q2=2 where k=9*10^9 I am lost after this I know I use

    asked on August 9, 2009
  18. physics

    Pelicans tuck their wings and free-fall straight down when diving for fish. Suppose a pelican starts its dive from a height of 15.0 m and cannot change its path once committed. If it takes a fish 0.25 s to perform evasive action, at what minimum height

    asked on July 18, 2011
  19. Math

    A chord is 4cm from the centre of a circle of radius 7cm. Calculate (a)the angle subtended by the chord at the centre (b) the length of the minnor arc cut off by the chord

    asked on June 5, 2019
  20. physics

    The resultant of two forces X and Y will be the greatest when the angle between X and Y is:

    asked on November 6, 2017
  21. Chemistry

    Consider two flasks. What are the final partial pressure of H2 and N2 after the stopcock between the two flasks is opened? Assume the final volume is 3.00 L. What is the total pressure in torr? Flask 1: 2.00 L H2, 475 torr Flask 2: 1.00 L N2, 0.200 atm

    asked on April 6, 2017
  22. Maths

    Make r the subject of formula t=2πr(r+h)

    asked on May 6, 2018
  23. chem

    a) Co(H2O)6^2 + 4 Cl^‐1 (aq) ⇄ CoCl4^‐2 (aq) + 6 H2O (l) Rewrite the net ionic equation above including the energy term where appropriate. The Delta H for this reaction is +50 kJ/mol. b) Silver chloride (AgCl) is a white solid. For the equilibrium

    asked on October 4, 2015
  24. Statistics

    Cellular Phone Sales The probability that a cellular phone company kiosk sells X number of new phone contracts per day is shown below. Find the mean, variance, and standard deviation for this probability distribution. X 4 5 6 8 10 P (X) 0.4 0.3 0.1 0.15

    asked on April 10, 2012
  25. Vectors

    Given the vectors below, determine the resultant and the equilibrant using trigonometry. Show all your steps. 330.0 newtons @ 125 degrees 250.0 newtons @ 60.0 degrees

    asked on September 2, 2010
  26. economics-Budget Constraint & Utility

    Sally is a frequent flyer whose fares are reduced through coupon offerings. She receives a 20% reduction on fares after she flies 20,000 miles, and 40% reduction after she flies 40,000 miles. a) Illustrate her budget constraint. b) Illustrate how her level

    asked on October 26, 2009
  27. Physics

    A small, circular washer of radius a = 0.750 cm is held directly below a long, straight wire carrying a current of I = 13.0 A. The washer is located h = 0.495 m above the top of a table (see figure below). Assume the magnetic field is nearly constant over

    asked on April 17, 2017
  28. Fiance

    What must be the price of a $10,000 bond with a 6.5% coupon rate, semi-annual coupons, and two years to maturity if it has a yield to maturity of 8% APR?

    asked on March 29, 2014
  29. physics

    Determine the stopping distances for an automobile with an initial speed of 95km/h and human reaction time of 1.0s: (a) for an acceleration a= -5.2m/s^2 (b) for a= -6.7m/s^2

    asked on July 10, 2011
  30. Finance

    If $12,000 is invested in a certain business at the start of the year, the investor will receive $3,600 at the end of the next four years. What is the present value of this business opportunity if the interest rate is 7% per year?

    asked on March 29, 2014
  31. math

    if (3-x), (6),(7-x) is a geometric sequence calculate (a)the two possible values of x (b) common ratio (c) sum of the sequence

    asked on March 15, 2019
  32. algebra

    How long does it take your money to double if it is left in an account for 20 years and earns 8.5% interest compounded continuously?

    asked on February 25, 2019
  33. Differential Equations

    A college professor contributes $5,000 per year into her retirement fund by making many small deposits throughout the year. The fund grows at a rate of 7% per year compounded continuously. After 30 years, she retires and begins withdrawing from her fund at

    asked on March 4, 2014
  34. Science

    Can anyone give me an acrostic poem on lithosphere?

    asked on November 7, 2010
  35. Chemistry Heat

    4Fe + 3O2 ---> 2Fe2O3 Delta H -1652 kJ How much heat is released when 10 g Fe and 2 g O2 are reacted.

    asked on April 8, 2017
  36. Physics

    There is a 85uC point charge at the origin. Find the electric field at the point x3= -45cm , y3= 55cm (5.85*10^5)(-.45+.75)/(-.45^2+.75^2)^3/2 am I totally off The previous questions before this were to find at x1=40cm y1=0 and x2=65cm y2=65cm I figured

    asked on August 9, 2009
  37. English

    Directions: Revise the following sentences to eliminate unnecessary shifts in tense, mood, voice, or person and number and between direct and indirect discourse. Most of the items can e revised in more than one way. Examples: • When a person goes to

    asked on November 4, 2011
  38. Finance

    What is the coupon rate of a two-year, $10,000 bond with semiannual coupons and a price of $9,543.45, if it has yield to maturity of 6.8%?

    asked on March 29, 2014
  39. Chemistry

    A sample of Helium occupies 200 L at 30ºC under a pressure of 841 torr. What is the volume it occupies at standard temprature and pressure (STP)?

    asked on April 21, 2017
  40. Chemistry

    A 30 g sample of water at 280 K is mixed with 50 g water at 330 K. Calculate the final temperature of the mixture assuming no heat loss to the surroundings.

    asked on April 9, 2017
  41. Maths

    A box is made of wood 5cm thick, its internal dimension are 10cm by 8cm by 11cm, what is the volume of the wood in the box

    asked on April 20, 2016
  42. physics

    A person who weighs 717 N is riding a 80-N mountain bike. Suppose the entire weight of the rider plus bike is supported equally by the two tires. If the gauge pressure in each tire is 8.10 x 105 Pa, what is the area of contact between each tire and the

    asked on August 16, 2015
  43. Vectors

    Given vectors A = -4.8i + 6.8j and B = 9.6i + 6.7j, determine the vector C that lies in the xy plane perpendicular to B and whose dot product with A is 20.0.

    asked on September 28, 2010
  44. physics

    How much work isneeded to stop a 20g bullet moving with a speed of 150m/s

    asked on March 1, 2017

    A uniform beam of length L whose mass is m, rest with its ends on two digital scales ( Figure 13.2). A block whose mass is M rests on the beam, its center is one-fourth away from the beam's left end. What do the scales read ?

    asked on May 21, 2013
  46. Chemistry

    So Ag+ + Cl- ---> AgCl and delta H is -65.5 kJ. I'm supposed to calculate delta H when one mole of AgCl dissolved in water, so 1 mol AgCl *(65.5 kJ/1mol Agcl) right? But the answer is 65.5 kJ, and why is it positive, not negative, is my question.

    asked on April 8, 2017
  47. Chemistry

    The reaction Fe + Br2 ---> FeBr2 Delta H = -249.8kJ Calculate delta H when 10.0 g of FeBr2 is formed.

    asked on April 8, 2017
  48. math

    A model of a rectangular patio at a landscaping business will be enlarged by a scale factor of 2 when it is installed in a customer’s back yard. The area of the new enlarged patio will be 160 square feet. Which is the area of the landscaper’s model? 10

    asked on April 18, 2017
  49. science

    A mass 10kg moves with a velocity of 4m/s .fin d the kinetic energy

    asked on March 3, 2019
  50. Maths

    A man spent one fourth of his monthly salary on rent, two fifth of the remaining on food and one sixth of still remained on drinks. What fraction did he spent on drinks

    asked on January 20, 2018
  51. Chemistry

    A is a solution of hydrochloric acid containing 3.650g of HCl in 1dm3 of solution. B is a solution of impure sodium carbonate. 25cm3 of B require 22.7cm3 of A for complete reaction. Given that 5.00g of impure B was dissolved in1dm3 solution,what is the

    asked on February 23, 2017
  52. Chemistry

    Calculate the concentrations of Cd2 +, [Cd (CN) 42] and CN at equilibrium when they dissolve 0, 42mol of Cd(NO3)2, molarity= 2.50 M Kf =7.1x10^16

    asked on April 23, 2016
  53. statistics

    A company produces steel rods. The lengths of the steel rods are normally distributed with a mean of 121.2-cm and a standard deviation of 1.8-cm. Suppose a rod is chosen at random from all the rods produced by the company. There is a 23% probability that

    asked on October 18, 2011
  54. physics

    An unmarked police car traveling a constant 90 km/h is passed by a speeder. Precisely 2.00 s after the speeder passes, the police officer steps on the accelerator. If the police car accelerates uniformly at 2.00 m/s^2 and overtakes the speeder after

    asked on July 12, 2011
  55. Physics

    a boat sails 150km N60°E, then 100km West. What is it's displacement from its starting point?

    asked on January 25, 2017
  56. Physics

    A 900-kg merry-go-round (a flat, solid cylinder) supports 10 children, each with a mass of 50.0 kg, located at the axis of rotation (thus you may assume the children have no angular momentum at that location). You need to describe a plan to move the

    asked on April 22, 2016
  57. Written Communication

    At the library, the quickest way to locate varied, reliable information for your research paper is to A. check the encyclopedias. B. search the card catalog for related titles. C. ask the reference librarian. D. check the Readers' Guide.

    asked on January 21, 2015
  58. physics

    A block with mass = 5.0 rests on a frictionless table and is attached by a horizontal spring ( = 130 ) to a wall. A second block, of mass = 1.35 , rests on top of . The coefficient of static friction between the two blocks is 0.40. What is the maximum

    asked on January 24, 2013
  59. Math

    how do you solve? kim's mom is 47 years old. in 5 years her mother will be 10 years older than twice what kim's age will be. how old is kim now?

    asked on September 10, 2015
  60. algebra1

    Melissa wants to figure out how many fish live in a small lake by her house .She ccatces 15 fish and tags the (safely).Shethen outs thoes fish back in the lake .Then next day ,she catches 28 fish .of those 28 fish, 3 of them have the tags on them.About how

    asked on August 22, 2015
  61. Spanish-SraJMcGin please check

    I had asked a question the other day but I'm not sure if I'm understanding this- it was a comparison-You said this as a comment: Spanish-8th grade - SraJMcGin, Thursday, October 20, 2011 at 4:02pm 3. also = de las tres actividades Also, #3 is different

    asked on October 22, 2011
  62. math

    If 16 men can construct 800 tables in 9 days how long will it take 15 men to construct 1000 tables if they work at the same rate

    asked on June 9, 2017
  63. Chemistry

    What mass of zinc would need to react with hydrochloric acid in order to produce 25.0 mL of hydrogen gas collected over water at 25 degrees celsius and 105 kPa. How do you solve this using the combined gas laws? The answer is 0.067 grams but how do you get

    asked on April 7, 2017
  64. physics

    It the specific gravity of mercury is 13.6 and the atmospheric pressure is 70cm of mercury, what is the total pressure of the gas supply in cm of water if the height of water is increase by 3cm?

    asked on May 13, 2014
  65. Science

    Acetylene gas c2h2 reaction cac2+2h2o. C2h2+Ca(oh)2 how many moles of cac2 needed to prepare 10.0 g c2h2 please show work and answer soon final question on big test review

    asked on February 17, 2014
  66. reading

    Which of the following is an example of active reading? A. Skimming over information and taking notes. B. Reviewing a chapter, question as you read, and review notes. C. Speed reading and taking notes in your own words. D. Both B & C.

    asked on February 28, 2013
  67. chemistry

    concentrated sulfuric acid has a density of 1.84 g/ml. calculate the mass in grams of 1.00 liter of this acid.

    asked on September 22, 2011
  68. Vectors

    Two vectors, A and B, are added by means of vector addition to give a resultant vector R. The magnitudes of A and B are 9 m and 8 m, respectively, and they can have any orientation. What are the maximum and minimum possible values for the magnitude of R?

    asked on September 2, 2010
  69. Chemistry

    In a coffee cup calorimeter, 2.00 g of potassium hydroxide are mixed with 200.0 g of water at an initial temperature of 25.00C. After dissolving the salt, the final temperature of the solution is 27.33C. What is the heat change for the dissolution of

    asked on April 9, 2017
  70. Chemistry

    Please help me out... The pressure of a container of fluorine gas with a volume of 1.5L is 678mmHg at 55.0*C. a. If the volume of the fluorine gas increases to 5.0L, what would be the pressure of the gas in atm? The amount and tempature of gas are

    asked on November 19, 2011
  71. Chemistry

    What volume of gas can be produced in a lab where pressure is 16.0 psi and temperature is 25 C if you collect it over water from the reaction of 50g of ammonium sulfate with 50g of aluminum hydroxide. The equation for the reaction is: 3(NH4)2SO4 + 2Al(OH)3

    asked on April 7, 2017
  72. English 1101 composition & rhetoric

    Put these sentences in order 1-6, based on whether it is the TS(1), GD1(2), SD1(3), GD2(4), SD2(5), CS(6), of a body paragraph in a five paragraph essay. A) Benson claims that the typical family eats together once a week now; a family having dinner

    asked on September 4, 2012
  73. college math

    boat travels 160 miles downstream in the same time that it takes to go 96 upstream. the pead of the stream is 6 mph. what is the speed of still water

    asked on March 9, 2012
  74. economics-oligopoly

    Suppose there are only two producers, A and B, in a market producing the same good with the same total cost function TC=0.05 Q^2 +100. The market demand is given by Q=1000-5P. a) Find the equilibrium price and total output in the Bertrand model. b) Find

    asked on March 24, 2010
  75. physics

    True or false questions a)Rubbing a polythene rod with a duster gives the rod extra negative charge. b)Rubbing a polythene rod with a duster takes away positive charge from the duster. c)The duster will have the same charge as the polythene rod it has

    asked on February 8, 2009
  76. math

    A baseball diamond is a square with each side 90 feet long. What is the straight-line distance from third base to first base? (Round your answer to the nearest tenth.)

    asked on February 1, 2017
  77. physics

    The Eiffel Tower is a steel structure whose height increases by 19.0 cm when the temperature changes from -9 to +41 oC. What is the approximate height (in meters) at the lower temperature?

    asked on August 16, 2015
  78. south al

    For a hypothetical normal distribution of test scores, approximately 95% fall between 38 and 62, 2.5% are below 38, and 2.5% are above 62. Given this information, (a) the mode=_____ and (b) the standard deviation=_____.

    asked on March 30, 2013
  79. math

    what is the estimated product of 3 2/3 x 5 1/9

    asked on February 15, 2012
  80. Economics(12 Multiple Choice)

    1. John Maynard Keynes said business investment is determined mainly by a. the state of business confidence b. expectations about the future c. psychological perceptions about the economy d. all of the above 2. Assume that the Canada experiences higher

    asked on November 26, 2009
  81. chemistry

    Calculate the mass of marble chips that produce 20 grams of carbon (iv) oxide .when reacted with dilute hydrochloric acid (c=12,O=16,Ca=40)

    asked on May 2, 2017
  82. math

    The north wall of a barn is a rectangle 25 feet high and 60 feet long. There are five windows in the wall, each 8 by 10 feet. If a gallon of paint will cover 275 ft2, how many gallons of paint must the painter buy to paint the wall?

    asked on February 1, 2017
  83. math

    The number of dogs and chickens on a farm add up to 14. The number of legs between them is 36. How many dogs and how many chickens are on the farm if there are at least twice as many chickens as dogs

    asked on August 30, 2012
  84. English

    Revise the following sentences to eliminate unnecessary shifts in tense, mood, voice, or person and number and between direct and indirect discourse. Most of the items can e revised in more than one way. 1. The greed of the 1980s gave way to the

    asked on November 4, 2011
  85. Econ-expected utility & insurance

    John is a professional football player and next year will be able to sign a $25 million contract if he does not get injured this year. If he gets injured this year, his value will be significantly reduced and he will only be able to sign a contract for $5

    asked on October 30, 2009
  86. Physics

    The Earth is surrounded by an electric field on its surface that points toward the center of the Earth with an average magnitude of 150 N/C. If there is an electron that is released in vacuum at the Earth’s surface, what will the acceleration due to the

    asked on August 10, 2009
  87. physics

    In using a pulley system, an effort of 100N is needed to raise steadily a load of 800N (a) what is the mechanical advantage?. Data effort=100N load=800N M.A=load/Effort M.A=800N/100N M.A=8

    asked on March 8, 2017
  88. MATH

    IF LOG10 A=4,WHAT IS A?

    asked on January 2, 2017
  89. physics

    The brass bar and the aluminum bar in the drawing are each attached to an immovable wall. At 21.3 °C the air gap between the rods is 1.70 x 10-3 m. At what temperature will the gap be closed?

    asked on August 16, 2015
  90. Physics 2A

    A position vector has an x component of -2.5 m and a y component of 4.2. (a) What is the vector's magnitude and directions? b) suppose a spider took 10 minters to first walk -2.5m in the x direction and then 17 mintures 4.2 m in the y direction? Find the

    asked on September 9, 2012
  91. Life orientation

    Alcoholism is a human factor that may cause ill health, accident, crises or disaster

    asked on April 12, 2012
  92. mercy land

    the 2nd, 3rd, and 4th term of an arithemetic progression are x-2, 5 and x+2 respectively, calculate the value of x and hence find the 20th term..

    asked on November 8, 2011
  93. statistics

    According to a bank, the time taken by its customers to use cash dispensing machines is normally distributed with a mean of 18 seconds and a standard deviation of 3 seconds. I) What is the probability that a customer selected at random takes less than 13

    asked on November 5, 2011
  94. mathematics

    Find the equation of the parabola with the vertex at the origin and directrix y =5

    asked on August 3, 2011
  95. Math 10+

    Write an expression with an exponent that is equvalent to 1/8

    asked on February 28, 2011
  96. Science

    How is radiotion different from convection and conduction? What happen to convection currents when a fluid reaches a constant temperature?

    asked on October 10, 2010
  97. US History

    1)Slave rebellions in the colonies were a result of a)harsh controlling African Americans' activities b)economic downturns c)the spread of democracy d)worsening conditions aboard slave ships I think C ? 2)The Green Party and Farmers' Alliances both called

    asked on August 9, 2010
  98. microeconomics

    Fact 1: "The substitution effect(SE) must ALWAYS be negative (i.e. goes in the opposite direction to the change in PRICE). The income effect(IE) can be either positive or negative." Fact 2: "SE and IE can go in the same direction or they can go in opposite

    asked on October 18, 2009
  99. Engineering

    Based on the force vector that is hown, I have to determine the x and y vector components. |\ fy=?| \ f= 200 lb | \ |___\ fx=? How do I do this with only one side given and the given 90 degree angle

    asked on August 8, 2009
  100. Engineering

    There is a shape that has a right triangle on top of a square, I need to find the area of the shape H1|\ | \ | \ | |H2 |___| B B=20Ft H2= 75lb/ft H1= 150 lb/ft I got 600 for the total area, am I close

    asked on August 7, 2009


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