Most popular questions and responses by jessica
  1. help plzzz


    asked on December 3, 2008
  2. Chemistry

    Classify the possible combinations of signs for a reaction's ∆H and ∆S values by the resulting spontaneity. A) Spontaneous as written at all temperatures. B) Spontaneous in reverse at all temperatures. C) Spontaneous as written above a certain

    asked on November 9, 2011
  3. Chemistry

    How many grams of dry NH4Cl need to be added to 2.10L of a 0.600M solution of ammonia,NH3 , to prepare a buffer solution that has a pH of 9.00? Kb for ammonia is 1.8x10^-5. I just wanted to make sure I dd this write, can you please check my work? Thank

    asked on October 8, 2011
  4. Math

    A camper attaches a rope from the top of her tent, 4 feet above the ground, to give it more support. If the rope is 8 feet long, about how far will the stake need to be from the middle of her tent?

    asked on December 27, 2017
  5. Physical Science

    A bicycle and its rider together have a mass of 80 kg. If the bicycle's speed is 6m/s, how much force is needed to bring it to a stop in 4 seconds

    asked on February 1, 2012

    A scientist is trying to determine the identity of an element. It is highly reactive in water and forms an ionic bond with chlorine. It is also very shiny. The element is likely A. From Group 17 ********** B. From Group 1 C. From Group 15 D. A Noble Gas

    asked on January 28, 2014
  7. chemistry

    A sample of propane(c3h8)has 3.84x10^24 H atoms. a) how many carbon atoms does the sample contain? b) what is the total mass of the sample?

    asked on January 15, 2011
  8. calculus

    In the early 1960s, radioactive strontium-90 was released during atmospheric testing of nuclear weapons and got into the bones of people alive at the time. If the half-life of strontium-90 is 27 years, what fraction of the strontium-90 absorbed in 1962

    asked on July 3, 2012
  9. Physics

    Two blocks of masses m1 = 2.00 kg and m2 = 3.70 kg are each released from rest at a height of h = 5.60 m on a frictionless track, as shown in the figure below, and undergo an elastic head-on collision. (Let the positive direction point to the right.

    asked on October 29, 2012
  10. physics

    A spring has an unstretched length of 10 cm . It exerts a restoring force F when stretched to a length of 12 cm . For what total stretched length of the spring is its restoring force 3F? At what compressed length is the restoring force 2F? I keep doing

    asked on April 11, 2016
  11. english

    What elements of the Restoration comedy are seen in The Importance of Being Earnest? (5 points)

    asked on April 25, 2012
  12. Calculus

    A particle moves along line segments from the origin to the points (3, 0, 0), (3, 3, 1), (0, 3, 1), and back to the origin under the influence of the force field F(x, y, z) = z2i + 5xyj + 4y2k. I have tried multiple times to solve this problem but the

    asked on December 8, 2014
  13. Algebra

    A can of soda is placed inside a cooler. As the soda cools, its temperature T(x) in degrees Celsius is given by the following exponential function, where is the number of minutes since the can was placed in the cooler. T(x)=-22+44e^-0.03x Find the initial

    asked on June 15, 2011
  14. Chemistry

    Two 20.0-g ice cubes at –20.0 °C are placed into 295 g of water at 25.0 °C. Assuming no energy is transferred to or from the surroundings, calculate the final temperature of the water after all the ice melts. Heat capacity of H2O(s)=37.7J Heat capacity

    asked on June 27, 2013
  15. Chemistry

    Refer to the following equation: 4NH3 + 7O2= 4NO2 +6HO, How many moles of ammonia would be required to produce 11.9 mol of water? Can you please walk me through the steps on how to figure this problem?

    asked on March 16, 2012
  16. Chemistry I - University Level

    Suppose 5.87 g of barium acetate is dissolved in 300. mL of a 71.0 m M aqueous solution of sodium chromate. calculate the final molarity of barium cation in the solution. You can assume the volume of the solution doesn't change when the barium acetate is

    asked on September 27, 2015
  17. Math, algebra!! Please help!!!!!!

    Using the numbers 5, 8, and 24, create a problem using no more than four operations (addition, subtraction, multiplication, division, square, square root, cube, cube root) where the solution will be an irrational number. Explain why the result of your

    asked on November 13, 2012
  18. Pre-Calc

    The Greek mathematician Eratosthenes (ca. 276-195 B.C.) measured the circumference of the earth from the following observations. He noticed that on a certain day the sun shone directly down a deep well in Syene (modern Aswan). At the same time in

    asked on March 16, 2012
  19. Science

    When evolution was first proposed, which of the following was used as evidence to support the idea? 1.observations of nature 2.laboratory experiments 3.extensive fossil collections 4.genetic sequences I think its either 1 or 4

    asked on October 29, 2014
  20. Chemistry

    The density of aluminum is 2.70g/cm3. If a cube of aluminum weighs 13.5 grams whatis the length of the edge of the cube. I need help with the formula to figure this one out.

    asked on June 1, 2011
  21. chemistry

    a)H2SO4 b)CuS c)HF d)Zn(NO3)2 Which are strong, weak, or non electrolytes. I was think A was strong B and C were weak and D is non

    asked on October 5, 2011
  22. Chemistry

    Which diffuses faster, the bad smell from a cat-pan due to ammonia or an expensive French perfume with an average molecular weight of 170 g/mol? How much fast does the fast one diffuse?

    asked on March 31, 2010
  23. Chemistry

    I did a lab the other day where we separated a mixture of NaCl, SiO2, and CaCO3. The Mixture was made by my professor and we did not know the original amounts of each compound. After recovering all of the compounds we found that there was.. 36.4% NaCl

    asked on February 4, 2014
  24. physics

    A golf ball is struck with a five iron on level ground. It lands 92.7 m away 4.40 s later. What was (a) the direction and (b) the magnitude of the initial velocity?

    asked on February 12, 2012
  25. Social Studies

    What are some differences between the European and Taino (Native American) ways of life and cultures? Desperate for anything. I've been researching for hours but can't find ANYTHING.

    asked on September 19, 2014
  26. anatomy

    where are the shoulders relative to these parts? 1. throat (inferior) 2. hip (superior) 3. ears (inferior) 4. hands (superior) 5. eyes (inferior) will someone please take a look at my answers and tell my if i am right

    asked on August 19, 2011
  27. Chemistry (Regents level)

    1- In the reaction Fe2O3 + 3 CO = 2 Fe + 3 CO2, what is the total number of moles of CO used to produce 112 grams of iron? a) 1.0 b)2.0 c)3.0 d)4.0 2- Given the reaction: 4Al + 3O2 = 2Al2O3 How many moles of Al2O3 will be formed when 27 grams of Al reacts

    asked on February 23, 2008
  28. Geometry

    Two similar triangles have a scale factor of 3 : 5. The altitude of the larger triangle is 24 inches. What is the altitude of the smaller triangle?

    asked on May 16, 2016
  29. Geometry

    8. The lateral area of a cone is 555πcm^2. The radius is 15.1 cm. What is the slant height to the nearest tenth of a centimeter? A. 36.8 cm B. 11.7 cm C. 83.8 cm*** D. 25.5 cm 10. What is the volume of the given prism? Round the answer to the nearest

    asked on December 18, 2017
  30. math

    use inductive reasoning to determine the units digit of the number 2^44 the unit digit of 2^44 is_____ powers of 2- 2^1=2 2^2=4 2^3=8 2^4=16 and so on that last one they have is 2^12 so 2^44 would be 1.7592188?

    asked on June 2, 2015
  31. Chemistry

    Determine the number of grams of water which are required to dissolve a mixture of 25 g of KNO3 and 2.0 g of CuSo4 * 5H20 AT 100 Degrees celscius?

    asked on February 9, 2011
  32. maths!

    the formula h=15t-5t^2 gives the height 'h' metres of a ball, 't' seconds after it is thrown up into the air. (i) find the times when the height is 10m (ii) after how long does the bal hit the ground? ive figured out that the answer to (i) is t= 1 or 2 by

    asked on August 6, 2008
  33. chemistry

    What is the major difference between the two-dimensional and three- dimensional models of ethane and methane? When might you choose to use a two-dimensional model rather than a three-dimensional model when representing one of the molecules?

    asked on September 30, 2013
  34. language arts

    Which question should you ask during your third read of the multi draft reading process

    asked on February 5, 2019
  35. English

    (I just need 2 writer ideas) In the middle of the 19th century, political philosopher Alexis de Tocqueville claimed, "The inhabitants of the United States have...properly speaking, no literature." In other words, de Tocqueville believed that America’s

    asked on January 7, 2015
  36. physics

    In designing rotating space stations to provide for artificial-gravity environments, one of the constraints that must be considered is motion sickness. Studies have shown that the negative effects of motion sickness begin to appear when the rotational

    asked on December 19, 2010
  37. Biology

    I would like some help if that is OK, like soon!:) 1.) A group of scientists proposes an idea that a chemical compound will enable bean plants to grow faster. They grow one group of bean plants in the presence of the compound and another group in the

    asked on September 19, 2016
  38. Chemistry

    Calculate the enthalpy change for: C2H4(g) + H2 --> C2H6(g) delta Hrxn: H2(g) + 1/2O2 --> H2O (l) C2H4(g) + 3O2 --> 2H20(l) + 2CO2(g) C2H6(g) + 7/2O2(g) --> 3H20(l) + 2CO2(g) I know I have to flip the third reaction but I don't know what to do next

    asked on October 29, 2014
  39. Chemistry

    Identify the oxidation-reduction reactions among the following: 1. Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) 2. 2Na(s) + Cl2(aq) → 2NaCl(s) 3. 2Mg(s) + O2(g) → 2MgO 1 and 2 only 2 and 3 only 1 and 3 only All of 1, 2, and 3 None of 1, 2, and 3

    asked on October 2, 2016
  40. algebra

    for what value of x is the rational expression below equal to zero? 2-x/2+x

    asked on August 31, 2016
  41. English

    The title "another evening at the club" is close in meaning to "just another evening at the club" given the events of the story, what is the significance of this meaning? I need help explaining this. I have no idea how to word it

    asked on June 16, 2016
  42. chemistry

    Using the activity series, write a balanced chemical equation for the following reactions: 1. iron metal is added to a solution of copper (II) nitrate 2. zinc metal is added to a solution of magnesium sulfate 3. hydrobromic acid is added to tin metal 4.

    asked on March 27, 2011
  43. math

    In Philadelphia the number of hours of daylight on day t (where t is the number of days after Jan. 1) is modeled by the function L(t)= 12+2.83sin(2pi/365(t-365)) A) Which days of the year have about 10 hours of daylight? B) Which days of the year have more

    asked on August 13, 2011
  44. American Government

    1. Thomas Hobbes and John Locke were European philosophers who influenced American founding documents with which theory? A. social contract theory B. divine right of kings theory C. no taxation without representation theory D. equal pay for equal work

    asked on September 19, 2016
  45. Organic Chemistry

    Separation scheme for isolating benzoic acid Could you please show me a separation scheme for isolating benzoic acid from a reaction mixture if mixing a Grignard reagent phenylmagnesium bromide with dry ice (CO2) in ether? Thanks!

    asked on October 22, 2010
  46. Physics

    A student sits on a rotating stool holding two 3.4-kg objects. When his arms are extended horizontally, the objects are 1.0 m from the axis of rotation and he rotates with an angular speed of 0.75 rad/s. The moment of inertia of the student plus stool is

    asked on November 27, 2012
  47. Physical Chemistry

    A saturated solution of Na2SO4, with excess of the solid, is present at equilibrium with its vapor in a closed vessel. (a) How many phases and components are present? (b) What is the number of degrees of freedom o the system? Identify the independent

    asked on October 3, 2015
  48. nutrition

    A fatty acid that contains a chain of 10 carbons and one double bond is termed a: a)monounsaturated,medium chain fatty acid. b)saturated,medium chain fatty acid. c)monounsaturated,long chain fatty acid. d)saturated,long chain fatty acid.

    asked on January 21, 2009
  49. Chemistry

    What mass in grams of a 0.500 m(molal) solution of sodium acetate, CH3CO2Na, in water would you use to obtain 0.200mol of sodium acetate?

    asked on February 2, 2014
  50. math

    write the number of permutations in factorial form.then simplify. how many different ways can you and four of your friends sit in the backseat of a limousine? A)4!;24 B)4!;120 C)5!;120 D)5!;720

    asked on June 5, 2014
  51. Science

    The force of gravity of objects on the moon is approximately one-sixth of their value on Earth. Joe weighs 7633 N on earth. What will Joe's mass on the moon be?

    asked on February 10, 2017
  52. Pharmacy calculations

    Based on the formula below, what quantities of each are needed to make 180 ml of this lotion? Benzyl Benzoate 250 ml Triethanolamine 5 ml Oleic Acid 20 ml Purified water to make 1000 ml

    asked on June 27, 2018
  53. math

    below are the results of tossing a number cube 8 times find the experimental probability of tossing an even number. 3,4,1,2,5,1,6,5 1. 1/4 2. 3/8 3. 1/2 4. 5/8

    asked on June 5, 2014
  54. Chemistry

    Addition of which of the following substances will increase the solubility of CuCO3 (s) in water ? CuCO3 ---- Cu^2+ (aq) +2 CO3^2- (aq) 1. Aqueous hydrochloric acid 2. Aqueous sodium carbonate 3. Solid copper (II) carbonate a) 1 only b) 2 only c) 3 only d)

    asked on April 4, 2012
  55. Physical Science

    ​ A 3-kg stone is dropped from a height of 100 m.  Find its kinetic and potential energies when it is 50 m from the ground.  

    asked on February 17, 2012
  56. Math :(

    Gil rolls a number cube 78 times. How many times can he expect to roll an odd number greater than 1??

    asked on April 30, 2012
  57. Geometry

    What does the diameter of a sphere join? any two points on the sphere any two points on the sphere and contains the center

    asked on February 24, 2016
  58. Math

    The planet Mercury is approximately 6 x 10^7 miles from the Sun. The distance between the Sun and Mars is approximately 2 x 10^8 miles. ABOUT how many times farther from the Sun is Mars than Mercury? 2 3 20 30 I got B? Can you please check? Thank you!!

    asked on December 27, 2017
  59. Chemistry

    Heat is given off when hydrogen burns in air according to the equation: 2H2 + O2 ---> 2H2) What is responsible for the heat? I know the answer is froming hydrogen-oxygen bonds gives off energy, but why?

    asked on January 17, 2014
  60. chemistry

    The pH of a 0.55-M aqueous solution of hypobromous acid, HBrO, at 25°C is 4.48. What is the value of Ka for HBrO? how do you solve for Ka?

    asked on November 23, 2010
  61. Chemistry

    The energy used to power one of the Apollo lunar missions was supplied by the following overall reaction: 2N2H4 + (CH3)2N2H2 + 3N2O4 -> 6N2 + 2CO2 + 8H2O For the phase of the lunar module ascended from the surface of the moon, a total of 1200kg N2H4 was

    asked on February 6, 2011

    10. Which of the following statements is true regarding the Korean War? A. Stalin approved the North Korean attack in advance. B. Stalin was outraged by the North Korean attack on South Korea. C. Both Stalin and Mao expected the American response to the

    asked on September 3, 2012
  63. Physics

    A 57 kg boy and a 45 kg girl use an elastic rope while engaged in a tug-of-war on a frictionless icy surface. If the acceleration of the girl toward the boy is 1.5 m/s2, determine the magnitude of the acceleration of the boy toward the girl. Answer in

    asked on October 14, 2012
  64. Physics

    Two hockey pucks of equal mass are involved in a perfectly elastic, glancing collision, as shown in the figure below. The orange puck is initially moving to the right at voi = 3.95 m/s, when it strikes the initially stationary blue puck, and moves off in a

    asked on November 6, 2016
  65. PHYSICS!!

    Squids and octopuses propel themselves by expelling water. They do this by taking the water into a cavity and then suddenly contracting the cavity, forcing the water to shoot out of an opening. A 6.50 daN squid (including the water in the cavity) that is

    asked on April 11, 2016
  66. Chemistry Lab

    Suppose for the reaction of Cu(NO3)2 + NaOH, you have not added enough sodium hydroxide to precipitate all the copper as copper hydroxide Cu(OH)2. a)How could you tell that not all the copper had precipitated? b)what effect would this have on the final

    asked on October 18, 2011
  67. Mathematics

    A farmer keeps hens and rabbits on his farm. One day, he counted a total of 70 heads and 196 legs. How many more hens than rabbit does he have? Explain your working please. Your help is greatly appreciated.

    asked on January 15, 2012
  68. geometry

    Angle C is an inscribed angle of circle P. Angle C measures (-3x - 6)° and arc AB measures (-4x)° . Find x. circle P with points A, B, and C on the circle and inscribed angle A C B drawn Question 4 answers -2 -4 -6 -8

    asked on August 26, 2011
  69. math

    Suppose you have $60 to buy shrimp and chicken wings for a party. Shrimp costs $10/lb and wings cost $6/lb. Write and graph a linear equation that could be used to determine the number of pounds of each food that can be purchased with $60 Would I start

    asked on November 5, 2015
  70. Pre-Algebra

    The grocery store sells kumquats for $4.25 a pound and Asian pears for $2 a pound. Write an equation in standard form for the weights of kumquats k and Asian pears p that a customer could buy with $12.

    asked on April 25, 2012
  71. English

    What is moral lesson in Annabel Lee?

    asked on November 16, 2014
  72. College chemistry math ratio problem

    Earlier you determined that the proper ratio of packages of buns, packages of patties, and jars of pickles is 3:2:4. If you want to feed at least 540 people, but also maintain the proper ratio, what minimum number of packages of buns, packages of patties,

    asked on September 2, 2013
  73. Science

    A father swings his child around in a circle. The source of the centripetal force that keeps the child moving in a circle is _____. tension friction weight gravity

    asked on May 21, 2010
  74. Math/Algebra

    On Dolphin Beach, the high tide is 2.2 meters and only occurs at 12 a.m. and 12 p.m. The low tide is 1 meter and only occurs at 6 a.m. and 6 p.m. Which function models the height of the tide t hours after 12 a.m.? a. h(t)=0.6cos(πt/6)+1.6* b.

    asked on April 8, 2018
  75. Science Check answers

    2) What phenomenon naturally warms Earth's lower atmosphere and surface? • the formation of sunspots • changes in the shape of Earth's orbit • global warming (MY ANSWER) • the greenhouse effect 3) Which of the following is an example of human

    asked on April 29, 2016
  76. Chemistry

    Iron combines with oxygen and water from the air to form rust. If an iron nail were allowed to rust completely, one should find that the rust weighs: I know the answer is the rust should way more than the nail it came from but can someone explain why

    asked on January 17, 2014
  77. college chemistry

    Please identify the net ionic equation for Na3PO4 +ZnSO4=Zn3(PO4)2+ Na2SO4

    asked on September 27, 2010
  78. Connections math help

    the equation is 3d + 2 equals 29 can be used to find the height of a bean plant days after it was purchased how many days has it been since the plant was purchased A.7.6 B.8 C.9 D.10.3

    asked on April 26, 2017
  79. Chemistry

    If 3.50g of Na3Po4 and 6.40g of Ba(No3)2 are added together how many grams of Ba3(PO4)2 will be produced? Which is the limiting reactant? Please explains step by step THANK YOU

    asked on October 31, 2010
  80. AP Chemistry

    (a) When 300.0 milliliters of a solution of 0.200 molar AgNO3 is mixed with 100.0 milliliters of a 0.0500 molar CaCl2 solution, what is the concentration of silver ion after the reaction has gone to completion? (b)Write the net cell reaction for a cell

    asked on April 5, 2010
  81. Physics

    An elevator accelerates upward at 1.2 m/s2. The acceleration of gravity is 9.8 m/s2 . What is the upward force exerted by the floor of the elevator on a(n) 92 kg passenger? Answer in units of N

    asked on October 22, 2012
  82. Chemistry

    H2 + F2--> 2HF deltaH = 518.0 kJ H2 ----> 2H deltaH = 436.8 kJ F2 ---> 2F deltaH = 158.2 kJ (a) calculate Delta H for H + !@#$%^&> HF (b) what is the standard enthalpy change of formation of F2 Help please!!! i think this is easier than i'm making it. for

    asked on April 28, 2011
  83. Algebra

    Rachel and Lindsay are in third place in a race. Due to a time penalty, they must start the next leg 90 minutes after the second place team. If rachel and lindsay travel at an average rate of 16.8 mph and the second place team travels at an average rate of

    asked on February 8, 2012
  84. math

    Brian O'Reilly earns twice as much each week as a tutor than he does pumping gas. His total weekly wages are $150 more than that of his younger sister. She earns one quarter as much as Brian does as a tutor. How much does Brian earn as a tutor? Use a

    asked on August 19, 2009
  85. chemistry

    Use delta ( + or - ) to show direction of expected polarity? for each of the bonds indicated. do you use electronegative numbers? how? I know the answers (i have the book) i just want to know how im supposed to know it for a test. a) H3C - CL b) H3C - NH2

    asked on January 17, 2011
  86. Chemisty


    asked on October 23, 2008
  87. Math/Algebra

    The equation ​ yˆ=−6.2x2+41.5x−5.6 ​ approximates the average number of cars that pass through an intersection x hours after 3:00 p.m. What is the best estimate for the average number of cars that pass through the intersection at 5:30 p.m.? a. 35

    asked on April 8, 2018
  88. physics

    Earth has a mass of 5.98 × 1024 kg. The average mass of the atoms that make up Earth is 40 u. How many atoms are there in Earth?

    asked on September 1, 2011
  89. History

    2. In the space below, create a simple time line that traces the emergence of a constitutional monarchy in England during the seventeenth century. It is not necessary to include exact dates, but events should be in the correct order. Include at least eight

    asked on February 12, 2016
  90. physics

    Ball A is dropped from the top of a building of height h at the same instant that ball B is thrown vertically upward from the ground. When the balls collide, they are moving in opposite directions, and the speed of A is twice the speed of B. At what height

    asked on August 10, 2014
  91. History

    magine you work in a steel mill in a large industrial city in England in the late 1800s. You live in a neighborhood with other factory workers, and share the same living and working conditions they do. Write a letter to your representative in Parliament

    asked on March 16, 2016
  92. chemistry

    How could you separate lauric acid from a-naphthol?

    asked on June 12, 2011
  93. Calculus

    BoxedNGone truck rentals calculates that its price function is p(x)=160-2x,where p is the price (in dollars) at which exactly x trucks will be rented per day. Find the number of trucks that BoxedNGone should rent and the price it should charge to maximize

    asked on November 9, 2014
  94. Chemistry

    When a 3.80 g sample of magnesium nitride (MW 101g/mol) is reacted with 3.30 g of water, 3.60 g of MgO is formed. What is the percent yield of this reaction? Mg3N2 + 3 H2O --> 2 NH3 + 3 MgO

    asked on November 2, 2016
  95. physics

    Io, one of the moons of Jupiter, circles Jupiter once every 1.77 days. The radius of its orbit is 4.22 X 108 m. If this orbit is circular, what is the mass of Jupiter?

    asked on July 12, 2012
  96. Business Finance

    Jeff Jones earns$1200 per week. He is married and claims four withholding allowances. The FICArate is as follows 1.45%. To date his cumulative wages are $6000. Each paycheck, his employer also deducts $42.50 for health insurance. What is his net pay?

    asked on May 19, 2012
  97. Chemistry

    Light from three different lasers (A, B, and C), each with a different wavelength, was shined onto the same metal surface. Laser A produced no photoelectrons. Lasers C and B both produced photoelectrons, but the photoelectrons produced by laser C had a

    asked on March 6, 2015
  98. Math

    A triangle and trapezoid share a 15 inch base and a height of 10 inches. For what values of b is the area of the trapezoid less than twice the area of the triangle?

    asked on October 3, 2011
  99. Math

    If m and n are integers, which of the following must be an even integer? A. 2mn B. mn C. mn+2 d. mn-2 e. 3mn

    asked on August 25, 2015
  100. chemistry

    You have a sample of gas at -30 C. You wish to increase the rms speed by 12%. To what temperature should the gas be heated?

    asked on November 10, 2009


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