Popular questions and responses by danny
  1. chemistry

    In the reaction below, ΔH°f is zero for ___________. Ni(s) + 2CO(g) + 2PF3(g) = Ni(CO)2(PF3)2(l) Ni(s) CO(g) Ni(CO)2(PF3)2(l) both CO(g) and PF3(g) PF3(g)

    asked on January 31, 2015
  2. chemistry

    At a certain elevation, the boiling point of water is 98.5°C. How much energy is needed to heat 35.0 mL of water to the boiling point at this elevation if the water initially was at 23.4°C? (Cp=75.38J/(mol*C), d= 1.00g/mL)

    asked on April 1, 2015
  3. statistics

    A regression analysis between sales (in $1000) and advertising (in $100) resulted in the following least squares line: = 75 + 6x. This implies that if advertising is $800, then the predicted amount of sales (in dollars) is: A) $4875 B) $123,000 C) $487,500

    asked on August 18, 2009
  4. Physical Science

    Energy from the sun reaches Earth mostly by A. conduction. B. convection. C. radiation. D. thermal expansion. I think it's A.

    asked on September 3, 2013
  5. chemistry

    The Ka of hypochlorous acid (HClO) is 3.00×10-8 at 25.0°C. Calculate the pH of a 0.0385 M hypochlorous acid solution. A.1.41 B.7.52 C.-1.41 D.4.47 E.8.94 I chose B

    asked on March 21, 2015
  6. chemistry

    What is the approximate effective nuclear charge for arsenic ?

    asked on April 27, 2015
  7. Physics

    A merry-go-round is a common piece of playground equipment. A 2.4 m diameter merry-go-round with a mass of 300 kg is spinning at 22 rpm. John runs tangent to the merry-go-round at 5.0 m/s, in the same direction that it is turning, and jumps onto the outer

    asked on December 2, 2011
  8. chemistry

    How many calories are required to heat 25.0 g of platinum from 24.5 °C to 75°C (specific heat of platinum = 0.139 J/gK)? 1. 47 cal 2. 42 cal 3. 48 cal 4. 20 cal 5. 80 cal Thank you.

    asked on November 22, 2009
  9. Physics (Stress & Strain)

    A hole 3cm in diameter is to be punched out of a steel plate 8cm thick. The shear stress of the material is 670GPa. What load is required on the punch? 3cm = 0.03m 8cm = 0.08m Lateral surface area (As) = pi*D*h = 3.1416 * .03m * .08m = 3.1416 * .0024m =

    asked on June 26, 2013
  10. Chemistry

    The equation for the complete combustion of ethene (C2H4) is C2H4(g) + 3 O2(g) ==> 2CO2(g) + 2H2O(g) If 2.70 mol C2H4 is reacted with 6.30 mole O2, identify the limiting reagent. show all work.

    asked on March 27, 2010
  11. chemistry

    The enthalpy change for the following reaction is -483.6 kJ: 2H2(g) + O2(g) = 2H2O(g) Therefore, the enthalpy change for the following reaction is _______ kJ: 4H2(g) + 2O2(g) = 4H2O(g)

    asked on January 31, 2015
  12. Chemistry

    As a sample of the radioactive isotope 131 I decays, its half-life a)decreases b)increases c)remains the same

    asked on May 5, 2010
  13. math

    The measures of the three angles of a triangle are given. Find the value of x and state whether the triangle is acute, obtuse, or right. x + 10, x − 20, x + 25 I got x is 55 and it is an acute angle. Is that correct?

    asked on October 10, 2016
  14. Chemistry

    What is the symbol for an ion with 63 protons, 60 electrons, and 88 neutrons? If an ion contains 50 protons, 68 neutrons, and 48 electrons, what is its symbol? Please help me.. im soo lost in this problem!

    asked on July 24, 2008
  15. Physics

    A 225-kg crate is pushed horizontally with a force of 690 N. If the coefficient of friction is 0.20, calculate the acceleration of the crate.

    asked on November 17, 2012
  16. physics

    Two balls have their centers 2.0 m apart. One ball has a mass of m1 = 8.3 kg. The other has a mass of m2 = 5.9 kg. What is the gravitational force between them? (Use G = 6.67 10-11 N · m2/kg2.)

    asked on December 3, 2012
  17. Algebra 1

    a farmer raises chickens and cows. there are 34 animals in all. the farmer counts 110 legs total on these animals. how many chickens and how many cows are on this farm?

    asked on May 16, 2011
  18. physics

    A 100-kg crate, sliding on the floor, is brought to a stop by a 25-n force. What is the deceleration of the crate?

    asked on March 20, 2009
  19. physics

    calculate the horizontal force that must be applied to a 1-kg puck to make it accelerate on a horizontal friction-free air table with the same acceleration it would have if it were dropped and fell freely?

    asked on March 20, 2009
  20. chemistry

    How is the reaction quotient used to determine whether a system is at equilibrium? The reaction is at equilibrium when Q > Keq. At equilibrium, the reaction quotient is undefined. The reaction quotient must be satisfied for equilibrium to be achieved. The

    asked on February 25, 2015
  21. physics

    21. A traffic signal of mass 25.0 kg is suspended by two cables as shown in the diagram below. Solve for the tension in each cable each of the following scenarios: (a) θ1 = θ2 = 20.0°, and (b) θ1 = 20.0°, θ2 = 30.0°.

    asked on February 17, 2015
  22. Math

    Radio stations use three or four letters for their call letters(name). The first letter must be a W or K. How many different call letters are possible if repeated letters are allowed? And not allowed?

    asked on March 29, 2013
  23. Calculus. I need help!

    Write the composite function in the form f(g(x)). [Identify the inner function u=g(x) and the outer function y=f(u).] Then find the derivative dy/dx. y=√sinx √ is square root.

    asked on February 25, 2012
  24. chemistry

    Is the dissolution of borax in water a temperature dependent reaction or is it spontaneous at all temperatures at which water is liquid? I think its spontaneous at all temperatures when water is liquid because borax is a polar compound.

    asked on April 1, 2008
  25. chemistry

    Consider an electrochemical cell based on the reaction: 2H+(aq) + Sn(s) = Sn2+(aq) + H2(g). Which of the following actions would NOT change the measured cell potential? lowering the pH in the cathode compartment addition of more tin metal to the anode

    asked on April 19, 2015
  26. Chemistry

    A sprinter must average 24.0 mi/h to win a 100-m dash in 9.30 s. What is his wavelength at this speed if his mass is 84.5 kg?

    asked on October 5, 2014
  27. physics

    A highway curve with radius 1000ft is to be banked so that a car traveling 56.0mph will not skid sideways even in the absence of friction At what angle should the curve be banked?

    asked on March 9, 2015
  28. Velocity

    An object is thrown directly downwards from a height of 60m with an initial velocity of 11m/s. What will be its velocity on impact? v^2 = U^2 + 2as a= 9.81m/s^2 u = 11m/s s = 60m v^2 = 11m/s + 2 * 9.81m/s^2 * 60 = 1188.2m^2/s^2 = square root of

    asked on June 3, 2013
  29. Optics

    The famous Chinese magician Foo Ling Yu performs a classic magic trick using a concave mirror with a focal length of 1.6 m. Foo uses the mirror to produce an image of a light bulb that is the same size as the light bulb itself and is at the same location.

    asked on June 5, 2018
  30. Stress & Strain (Help Please)

    A tie bar is made of a material having a tensile strength of 231 MPa and has to carry a load of 255 kN. What id the diameter of the bar if a factor of safety of 7 is applied? ANS = 99.2 mm Cannot figure out how to get the answer. Need help please. Thank

    asked on August 10, 2013
  31. college algebra

    An open box is made from a square piece of cardboard 20 inches on a side by cutting identical squares from the corners and turning up the sides.(a) Express the volume of the box, V , as a function of the length of the side of the square cut from each

    asked on September 27, 2012
  32. chemistry

    Consider an electrochemical cell based on the reaction: 2H+(aq) + Sn(s) = Sn2+(aq) + H2(g). Which of the following actions would NOT change the measured cell potential? lowering the pH in the cathode compartment addition of more tin metal to the anode

    asked on April 16, 2015
  33. chemistry

    Calcium carbide (CaC2) reacts with water to form acetylene (C2H2) gas and calcium hydroxide (Ca(OH)2). If the ΔH for: CaC2(s) + 2H2O(l) = Ca(OH)2(s) + C2H2(g) is -127 kJ, then what is the enthalpy of formation for calcium carbide? The ΔH of formation for

    asked on January 31, 2015
  34. Math

    A spring is 25 cm long when stretched. The spring was stretched by 18% of its original length. Determine the original length.

    asked on December 21, 2013
  35. math

    What is the angle sum of a regular polygon with 7 sides

    asked on August 30, 2012
  36. Science

    Use the word bank below to answer the questions that follow: alleles mitosis DNA phenotype haploid codominance diploid meiosis incomplete dominance centromere reproduce RNA Genes are specific sections of ______________________.

    asked on October 5, 2020
  37. chemistry

    How many electrons does the Au+ ion have ? Enter an integer below without any letters or symbols.

    asked on April 15, 2015
  38. science

    A 5.0 kg model vehicle travelling at 14 m/s experiences a rocket boost of 85 N ( in the direction of motion) for 20 s What is the resulting speed? The answer is 350 but i don't know how to get to that answer

    asked on November 6, 2014
  39. Physics

    The Ultimate strength of a round steel rod is 630.000MPa. If a factor of safety of 5.000 is required, what is the maximum permissible load for the rod if it has a diameter of 3.000cm? ANS = kN (Round to 3 decimal places) Safety = 5.000 Rod diameter =

    asked on July 3, 2013
  40. Physics (Stress & Strain)

    What is the factor of safety of a steel hanger having an ultimate strength of 630.000MPa and supporting a load of 65000.000N. The steel hanger in question has a cross sectional area of 5.300cm. ANS = (Round to 3 decimal places) Load = 65000.000N ultimate

    asked on June 29, 2013
  41. Physics

    Camera lenses are described in terms of their focal length. A 50.0 mm lens has a focal length of 50.0 mm (a) A camera with a 50 mm lens is focused on an object 4.0 m away. Locate the image. (b) A 980 mm lens is focused on an object 125 m away. Locate the

    asked on May 21, 2013
  42. Physics

    One of the most powerful cranes in the world, operating in Switzerland, can slowly raise a load of 6000 tonne to a height of 12 m. (1 tonne = 1000 kg) The acceleration of gravity is 9.81 m/s2 . How much work is done by the crane? Answer in units of MJ I

    asked on February 26, 2013
  43. Chemistry

    5F2(g) + 2NH3(g) ==> N2F4(g) + 6HF(g) a)If you have 66.6 g NH3, how many grams of F2 are required for complete reaction? b)How many grams of NH3 are required to produce 4.65g HF? c)How many grams of N2F4 can be produced from 225g F2?

    asked on April 5, 2010
  44. chemistry

    The combustion reaction of acetylene gas is represented by this equation: 2C2H2(g) + 5 O2(g) ==> 4CO2(g) + 2H2O(g) How many grams of CO2 and grams of H2O are produced when 52.0g C2H2 burns in oxygen?

    asked on March 22, 2010
  45. global

    Why would so many women miners prefer to work in the mines without clothing? Why did the women need the heavy belts around their waists and chains between their legs?

    asked on February 24, 2010
  46. Physics

    If the soccer player kicks the ball with an initial velocity of 20 m/s at an angle of 45 degrees relative to the ground then what is the time it takes for the ball to reach the maximum height, what is the time of flight, what is the range, and what are the

    asked on September 18, 2020
  47. Physics

    a 47 kg person in a rollercoaster moving through the bottom of a curved track of radius 47.7 m feels a normal force of 895 N. What is the net centripedal force acting on the person

    asked on June 13, 2019
  48. Physics

    A train traveling at a speed of 110 km/h uniformly decelerates for 20 seconds. During that time it travels 450m. A) What is the acceleration? (m/s^2) B) What is its speed after deceleration? (km/h) A ANS = -.805m/s^2 B ANS = 52km s = 450m t = 20 seconds u

    asked on January 11, 2014
  49. English 3

    Young Goodman Brown is a dynamic character TRUE OR FALSE

    asked on November 7, 2012
  50. ENGLISH Types of business writing

    Assume that you’ve worked for the last five years as an administrative assistant for the Human Resources Department of Broadworth General Hospital. The Director of Human Resources, Miriam Hopkins, has charged you with organizing a two-hour training

    asked on April 2, 2012
  51. Chemistry

    KI+H2SO4 Write the balanced net ionic equation.

    asked on February 17, 2012
  52. Calculus

    A plane flying with a constant speed of 24 km/min passes over a ground radar station at an altitude of 8 km and climbs at an angle of 20 degrees. At what rate, in km/min, is the distance from the plane to the radar station increasing 2 minutes later?

    asked on March 1, 2010
  53. Math Trigonometry

    A plane flies in a direction of 85° from Chicago. It then turns and flies in the direction of 200° for 150 miles. It is then 195 miles from its starting point. How far did the plane fly in the direction of 85°? I am confused about aereal navigation. Can

    asked on May 19, 2016
  54. chemistry

    Which element is reduced in the unbalanced reaction below? I− + MnO4− + H+ = I2 + MnO2 + H2O I no reduction occurred in this reaction O H Mn

    asked on April 16, 2015
  55. Physics (Stress & Strain)

    A uniform bar 1.900 meters in length and having a cross sectional area of 11.000cm^2 is subject to a loading of 5450.000 Newtons. this load causes an extension to the bar length of 2.420mm. Calculate the stress and strain produced. 11cm = .11m 2.420mm =

    asked on June 26, 2013
  56. Acceleration

    Which of the following statements about acceleration is true. Acceleration is: A) time/ velocity B) force/ time C) the rate of change of displacement D) time/ force E) the result of an unbalanced force exerted on a body. ANS = E Is this correct??

    asked on June 3, 2013
  57. Math

    it costs $175 to rent a jet ski for 2 hours. it costs $300 to rent a jet ski for 4 hours. write an equation that represents y (in dollars) of renting a jet ski for x hours.

    asked on January 23, 2012
  58. statistics

    In a one-way ANOVA, there are three independent samples, with n1 8, n2 = 10, and n3 = 7. The calculated F-statistic is F = 3.95. At the 0.05 level of significance, what conclusion would be reached? Based on the F distribution tables, what is the most

    asked on August 4, 2009
  59. math

    A car is sold for $22,000. After one year, the value of the car is $16,500. Write an exponential function y to determine the value of the car after x years if the rate of decrease is the same each year.

    asked on October 31, 2020
  60. Economics Macro

    Suppose that real GDP per capita in the United States is $49,000. If the long-term growth rate of real GDP per capita is 1.6% per year, how many years will it take for real GDP per capita to reach $98,000?

    asked on January 25, 2016
  61. Algebra 2

    Amanda surveyed 20 juniors and seniors at Delamar high school to find the number of hours per week they spend working at part-time jobs. Her results are shown below. Juniors: 20,10,20,10,15,0,0,10,20,15 Seniors: 20,20,10,10,0,0,0,10,0,10 which statement

    asked on May 19, 2014
  62. HELP! HELP! HELP! Physics

    The surface density of a thin rectangle varies as: σ(x,y)= 14.0 kg/m2 + 9.00 kg/m4(x2+y2) The rectangle has a length L = 0.500 m and a width W = 1.500 m. Calculate Iz, the moment of inertia about the z-axis.

    asked on February 12, 2014
  63. grammar

    Which part of speech is the capitalized words in this sentence? Four score and seven years ago our fathers brought forth on this continent, a NEW nation, conceived in Liberty, and DEDICATED to the proposition that all men are created equal. Now we are

    asked on November 17, 2013
  64. Physics

    Simple Machines A simple wheel and axle has a wheel diameter of 2.3m and an axle diameter of 92mm. If an effort of 26N is required to raise a mass of 16 kg what is the efficiency of the machine? A- 2.46% B- 95.3% C- 24.1% D- 20.1% E- 65.5% I am having a

    asked on May 11, 2013
  65. Physics

    A Body with a mass of 150kg is located at a height of 45 m. If allowed to fell freely to the ground. What will be its velocity on impact? KE= 1/2*m*v^2 PE= m*g*h 1/2*m*v^2= m*g*h 1/2*150kg*45m*v^2= 150kg*9.81*45m 3375* v^2= 66217.5 3375*v^2/3375=

    asked on April 27, 2013
  66. math

    A steel tube has an outside diameter of 15 cm, an inside diameter of 13 cm,and is 3.7 m long. What is the volume of the steel contained in the tube in cubic cm is?

    asked on April 19, 2013
  67. Math

    Frank has 3 nickels, 5 dimes, and 2 quarters. What is the range, mean, median, and mode of the values of Frank's coins?

    asked on March 18, 2013
  68. math

    If the radius of this cylinder is doubled, its volume will be twice as much four times as much eight times as much is it four times as much?

    asked on April 4, 2011
  69. english

    "The editors . . . break those sequences up into quick jagged shots that key us up and keep us hyper-alert . . . we look hard at the screen to take it in." universality?

    asked on October 29, 2010
  70. Physic

    A 2.2 m-long string is fixed at both ends and tightened until the wave speed is 50 m/s. What is the frequency of the standing wave shown in the figure? Answer in Hz. I've been working on it for a while but cant figure out...

    asked on November 7, 2009
  71. Pre-Calculus

    A hemispherical bowl with a 30-centimeter radius contains some water, which is 12 centimeters deep. Find the volume of the water.

    asked on October 10, 2016
  72. math

    Sarah Meeham blends coffee for Tasi-Delight. She needs to prepare 140 pounds for blended coffee beans selling for $5.07 per pound. She plans to do this by blending together a high-quality bean costing $6.50 per pound and a cheaper bean at $2.50 per pound.

    asked on July 14, 2015
  73. chem

    The value for ΔH° for the reaction below is -72 kJ. How many kJ of heat are released when 1.0 mol of HBr is formed in this reaction? H2(g) + Br2(l) = 2HBr(g)

    asked on January 28, 2015
  74. chemistry

    Calculate the H3O+ concentration present in water under the following conditions. Enter your answer in scientific notation. a. [OH-] = 2.8 x 10-7 M b. [OH-] = 8.8 x 10-3 M c. [OH-] = 2.4 x 10-11 M everytime I do the problem In the calculator I get system

    asked on March 19, 2014
  75. Spanish

    ¿Con quién _____ tú el almuerzo? A. comparto B. compartes C. compartimos D. comparte B?

    asked on September 16, 2013
  76. Physical Science

    When opposite poles of two magnets are brought together, the poles A. attract each other. B. repel each other. C. cancel each other. D. cause a net force of zero. I think it's B.

    asked on September 3, 2013
  77. Acceleration

    Which of the following statements about acceleration is true. Acceleration is: A) time/ velocity B) force/ time C) the rate of change of displacement D) time/ force E) the result of an unbalanced force exerted on a body. ANS = E Is this correct??

    asked on June 3, 2013
  78. math

    The only defined term of those listed is: line angle plane point

    asked on April 13, 2011
  79. math

    Find the exact circumference of a circle with diameter equal to 8 ft. 8 ft. 16 ft. 64 ft. what equation would u use?

    asked on February 28, 2011
  80. english

    Which of the following topics relate directly to a work's authenticity? 1)believability of characters 2)the appeal of a certain guitar riff 3)sincerity expressed in a love song 4)the likely appeal to all teenagers 5)the way the setting matches the mood of

    asked on November 1, 2010
  81. english

    "He manages to portray tiny, random events as significant without the occasionally overblown melodrama . . . " so im suppose to Read the quote and choose its category. but i don't no what to do? these are my answer choices.. -universality -subject matter

    asked on October 28, 2010
  82. english

    An example of the frame story is _____. 1)"The Celebrated Jumping Frog of Calaveras County 2"The Lady, or the Tiger?" 3)"The Necklace" i think its number 1?

    asked on October 26, 2010
  83. Statistics

    What are the mean and standard deviation of the sampling distribution of ​? Round your results to the nearest penny.

    asked on November 8, 2020
  84. chemistry

    One of the ways to produce iron is to take iron(II) oxide and react it with carbon monoxide to get pure iron and carbon dioxide. The reaction is FeO(s) + CO(g) = Fe(s) + CO2(g). What is the partial pressure of CO2(g) if 2.00 atm of CO and excess iron(II)

    asked on February 28, 2015
  85. Chemistry

    Calculate the pH of a solution in which a. [H3O+] = 7.8 x 10-7 M pH = b. [H3O+] = 5.1 x 10-6 M pH = c. [H3O+] = 6.1 x 10-5 M pH = d. [H3O+] = 9.3 x 10-4 M pH = I get 8.1 9.5 9.1 6.7 but its wrong please someone help!

    asked on March 19, 2014
  86. calculus

    Imagine making a tent in the shape of a right prism whose cross-section is an equilateral triangle (the door is on one of the triangular ends). Assume we want the volume to be 2.2 m3, to sleep two or three people. The floor of the tent is cheaper material

    asked on December 10, 2013
  87. Physics

    A steel bar has a rectangular cross section measuring 1.000cm by 2.900cm and is 8.700m in length. A load of 189000.00N causes the bar to extend 1.500mm. Calculate the stress and strain produced. ANS 1 = kPa (3 decimal places) ANS 2 = (6 decimal places)

    asked on July 2, 2013
  88. physics

    Tom has a mass of 69.0 kg and Sally has a mass of 54.0 kg. Tom and Sally are standing 20.0 m apart on the dance floor. Sally looks up and sees Tom. She feels an attraction. If the attraction is gravitational, find its size. Assume that both Tom and Sally

    asked on December 3, 2012
  89. math

    Two similar polygons have areas of 16 square inches and 64 square inches. The ratio of a pair of corresponding sides is 1/4. True False its true?

    asked on April 6, 2011
  90. math

    When chords intersect in a circle, the vertical angles formed intercept congruent arcs. always sometimes never

    asked on January 6, 2011
  91. english

    "All the world is a stage, and all the men and women merely players." metaphor?

    asked on October 26, 2010
  92. Chemistry

    Identify the solvent and the solute in vinegar, a dilute aqueous solution of acetic acid.

    asked on April 13, 2010
  93. Math

    Gabriella’s travel shampoo bottle holds 1/2 cup of shampoo before leaving on vacation she filled the bottle to the top with 1/8 cup of shampoo how much shampoo was already in the bottle?

    asked on September 10, 2018
  94. Maths

    Have a question on complex numbers. Z1= 1+j2, Z2= 2+j5 Find total impedance in Cartesian and polar form of two impedances in parallel: 1/ZT = 1/Z1 + 1/Z2 I get to 39/58 + 83/58 j but then get a bit lost.

    asked on May 20, 2015
  95. physics

    How many kilometers would you have to go above the surface of the earth for your weight to decrease to 39{\rm \\%} of what it was at the surface? Express your answer using two significant figures.

    asked on March 9, 2015
  96. physics

    What is the mass of 5.00L of pure water?

    asked on January 28, 2015
  97. spanish

    Nosotros siempre _____ la comida. A. comparten B. comparto C. compartimos D. comparte A?

    asked on September 16, 2013
  98. Physical Science

    Which of the following is a heterogeneous mixture? A. water in a swimming pool B. sugar water C. a jar of mixed nuts D. stainless steel I think it's B.

    asked on August 27, 2013
  99. Physics- Simple machines

    A wheel and axle arrangement has an axle with a diameter of 25cm. A rope is wrapped around the axle and is supporting a load of 2 tonnes. 1) If the mechanical advantage of the system is 30, determine the diameter of the wheel___________m. 2)Determine the

    asked on May 12, 2013
  100. physics

    Early skeptics of the idea of a rotating Earth said that the fast spin of Earth would throw people at the equator into space. The radius of Earth is about 6400 km. Show why this objection is wrong by determining the following information. (a) Calculate the

    asked on December 6, 2012


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