Popular questions and responses by jessica
  1. 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
  2. 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
  3. Physics -- check answers please

    1. A boy pushes a car to slow it down while the car is rolling horizontally down the road. If the boy pushes backwards on the car with 10N of force as the car rolls forward 3.0m, the amount of work done by the boy is: a)-30 b)0 c)3.3 J d)30 N•m e)300J my

    asked on April 2, 2014
  4. Math

    Mr. Brown owned a house which he rented for $60 a month. The house was assessed at $9000. In 1975 the rate of taxation was increased from $25 to $28 per $1000 assessed valuation. By what amount should the monthly rent have been raised to absorb the

    asked on July 26, 2018
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. Physics multiple choice questions

    1. Which of the following energy transformations best describes the operation of a solar powered battery charger? (a) electrical energy --> thermal energy --> kinetic energy (b) nuclear energy --> potential energy --> chemical energy (c) thermal energy -->

    asked on April 8, 2014
  12. 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
  13. Probability

    When two fair six-sided dice are rolled, there are 36 possible outcomes. Find the probability that either doubles are rolled or the sum of the two dice is 8.

    asked on April 30, 2014
  14. Chemistry 151

    Of the following transitions in the Bohr hydrogen atom, the ____ transition results in the emission of the highest-energy photon. a.n=1, n=6 b.n=6, n=1 c.n=6,n=3 d.n=3,n=6 e.n=1,n=4

    asked on November 8, 2010
  15. Physics

    A 100N force acting on a lever 2m from the fulcrum balances an object 0.5m from the fulcrum on the other arm. What is the weight of the object(in newtons)?What is it's mass (in kg)?

    asked on January 19, 2015
  16. Interest

    You deposit $4000 in an account earning 5% interest compounded monthly. How much will you have in the account in 5 years? Use n=12 for monthly compounding,n=4 for quarterly compounding,n=2 for semiannual compounding, and n=1 for annual compounding.)

    asked on December 1, 2016
  17. geometric progression

    the 3rd term of a gpis 10 and the 6th term is 80 find the common ratio No2 if the 2nd term of a gp is 4 and the 5th term is 1over 16,the7th term is_

    asked on November 18, 2014
  18. Maths

    x is partly constant and partly varies with y.When y=5,x=19 and when y=10,x=34. (i) Find the relationship between x and y. (ii) Find x when y=7.

    asked on October 26, 2018
  19. geometry

    How much material would you need to fill the following cylinder? Radius 13 in. and Height 9 in. 39π in3 117π in3 1053π in3 1521π in3

    asked on July 21, 2020
  20. math

    You are dealt one card from a standard​ 52-card deck. Find the probability of being dealt a card greater than 2 and less than 7. I got 5x4=20/52=5/13

    asked on March 28, 2016
  21. Math

    1) Maria is 6 times as old as Tina. In twenty years, Maria will be only twice as old as Tina. How old is Maria now? Please explain how you got your answer. Thanks! 2) Rating. Relative speed of flow 10W. Half as fast as 5W 15W. Half as fast as 10W 20W. Half

    asked on January 15, 2018
  22. 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
  23. 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
  24. chemistry

    Write a balanced chemical reaction to show the dissociation of solid magnesium chloride (MgCl2) in water, indicate states of the reactants and products

    asked on October 15, 2010
  25. Math

    Use the display of data to find the standard deviation. A bar graph titled Score with a horizontal axis labeled from 5 to 11 in increments of 1 and a vertical axis labeled Frequency from 0 to 12 in increments of 2 contains three vertical bars with labels

    asked on April 1, 2017
  26. Calculas

    A box lid is to be made from a rectangular piece of cardboard measuring 72 cm by 216 cm. Two equal squares of side x are to be removed from one end, and two equal rectangles are to be removed from the other end so that the tabs can be folded to form a box

    asked on December 7, 2014
  27. 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
  28. English

    You are a speaker in a school debate on the topic boys should not help in the kitchen.Write your speech for or against the motion

    asked on July 18, 2020
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. 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
  37. 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
  38. 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
  39. Physics multiple choice questions

    1. Which of the following energy transformations best describes the operation of a solar powered battery charger? (a) electrical energy --> thermal energy --> kinetic energy (b) nuclear energy --> potential energy --> chemical energy (c) thermal energy -->

    asked on April 7, 2014
  40. Math

    A cone is 8cm high and its vertical angle is 62 degrees,find the diameter of its base

    asked on September 19, 2014
  41. Math

    Erica has 8 squares of felt, each with area 16. For a certain craft project she cuts the largest circle possible from each square felt. What is the combined area of the excess felt left over after cutting out all the circles? A) 4(4-pi) B) 8(4-pi) C)

    asked on November 11, 2017
  42. 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
  43. geometry

    Given the following probabilities, for what P(B) are events A and B independent? P(A)=1/2 P(A and B)=1/6 1/4 1/8 3/4 1/3

    asked on July 24, 2020
  44. Chemistry

    How could you separate a mixture of water, rock salt, sawdust, and iron filings? Would this require physical means, chemical means, or both?

    asked on September 17, 2018
  45. Discrete Math

    Find z so that 5% of the area under the standard normal curve lies to the right of z. the answer according to the book is 1.645, anyone got any ideas on how to get this?

    asked on January 21, 2013
  46. 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
  47. Physics

    Two point charges, Q1 = -7.0 and Q2 = 2.0 are located between two oppositely charged parallel plates, as shown in the figure . The two charges are separated by a distance of x = 0.33m . Assume that the electric field produced by the charged plates is

    asked on August 29, 2011
  48. English

    is a excitedness a word

    asked on August 11, 2020
  49. 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
  50. Math help 1 question!!!!!!!!

    14. Which statement is true? A. Every rational number is a square root. B. Every irrational number is a fraction. C. Every rational number can be written as a fraction. D. Every square root can be written as a whole number.

    asked on October 10, 2014
  51. medicine

    50 ml of a solution of 50% dextrose is added to a liter of 0.45% NaCl with 2.5% dextrose to yield a solution with a final dextrose concentration of what percent

    asked on September 23, 2010
  52. Physics university

    In a tennis match, a player wins a point by hitting the ball sharply to the ground on the opponent's side of the net. If the ball bounces upward from the ground with a speed of 17 m/s , and is caught by a fan in the stands with a speed of 12 m/s , how high

    asked on October 12, 2009
  53. math

    If 15 percent of n is 45 percent of 2003, what is the value of n? I think the answer to this is n=6009. Is this right?

    asked on December 10, 2008
  54. algebra

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

    asked on August 31, 2016
  55. 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
  56. Chemistry

    At a given temperature, the elementary reaction A B in the forward direction is first order in A with a rate constant of 2.60 x 10^-2 s^-1. The reverse reaction is first order in B and the rate constant is 8.50 x 10^-2 s^-1. What is the value of the

    asked on March 5, 2012
  57. Math

    Which ordered pair could be removed to make a function? {(1,3) (2,4) (3,4) (3,6) (5,10) (6,3)} A) (2,4) B) (3,4) C (1,3) D) (6,3)

    asked on December 27, 2017
  58. 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
  59. Math/calculus

    Tan 165° Use appropriate identity and evaluate

    asked on November 13, 2017
  60. math

    How many gram of sodium fluoride should be added to 100000 liter of drinking water containing 0.6 ppm of sodium fluoride to provide a recommended concentration of 1.75 ppm? Answer is 115 grams. I keep getting .115 g What am I doing wrong? Please help.

    asked on May 12, 2016
  61. 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
  62. chemistry

    why do we use the limiting reactant data to calculate delta h? why might it be important to know delta h prior to running a reaction?

    asked on November 13, 2014
  63. Physics -- check answers please

    1. Which of the following energy transformations best describes the operation of a solar powered battery charger? (a) electrical energy --> thermal energy --> kinetic energy (b) nuclear energy --> potential energy --> chemical energy (c) thermal energy -->

    asked on April 7, 2014
  64. chemistry

    Draw a line-bond structure for propene,CH3CH=CH2; indicate the hybridization of eachcarbon, and predict the value of each bond angle. Can someone explain the steps, im lost with how our teacher explained, about sp2 and sp3, ect. help?

    asked on January 11, 2011
  65. geometry

    Point B is at (3,1). For which segment is B a midpoint? AC¯¯¯¯¯¯¯¯ with endpoints at A(1,−1) and C(8,6) AC¯¯¯¯¯¯¯¯ with endpoints at A(1,−1) and C(5,3) AD¯¯¯¯¯¯¯¯ with endpoints at A(1,−1) and C(6,4) AC¯¯¯¯¯¯¯¯ with

    asked on July 6, 2020

    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
  67. 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
  68. Algebra

    Compute the value of the discriminant and give the number of real solutions to the quadratic equation. 2x^2+5x-7=0 Discrimnant= number of real solutions=

    asked on January 27, 2011
  69. Chemistry

    Balance the following by placing the correct coefficients in front of each formula _____ CaO + _____ P4O10 ______ Ca3(PO4)2 All the numbers are in subscript b. Using: ammonium nitrate → water + nitrogen I oxide, write a balanced using correct chemical

    asked on December 10, 2018
  70. Math

    A fair coin is tossed two times in succession. The set of equally likely outcomes is {HH, HT, TH, TT}. Find the probability of getting exactly one head. The probability of getting one head

    asked on March 23, 2017
  71. Mathematics

    An isosceles triangle has a vertical angle of 116 degrees and its base is 8cm long.calculate its height

    asked on September 19, 2014
  72. math

    The ABC Toy Company is creating two similar pieces for a board game as shown below. Find the value of b that makes the two pieces similar.

    asked on May 7, 2014
  73. mathematics

    Given that log5 3=0.683 and log5 7=1.209.without using calculator,evaluate (a) log5 1.4 b)log7 75 c) log3 125

    asked on April 16, 2014
  74. 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
  75. 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
  76. Chemistry

    Calculate the change in enthalpy when 52.0 g of solid chromium at 25°C and 1 atm pressure is oxidized. (H°f for Cr2O3(s) is –1135 kJ/mol.) 4Cr(s) + 3O2(g)  2Cr2O3(s) a. –1135 kJ b. –284 kJ c. –568 kJ d. +1135 kJ e. +568 kJ

    asked on July 1, 2013
  77. Chemistry

    Determine the enthalpy of the following reaction. 2M(s) + 3Cl2(g) ---> 2MCl3(s)

    asked on June 19, 2013
  78. Physics

    The figure below shows two current carrying wires and the directions of the currents they carry. The wires carry the following currents: I1 = 7.1 A and I2 = 8.9 A. Wire 1 is at (0, 5.8) mm; wire 2 is at (15.1, 0) mm; point P is at (15.1, 5.8) mm. Wire 1 is

    asked on April 10, 2012
  79. 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
  80. CALC

    An open box is to be constructed so that the length of the base is 4 times larger than the width of the base. If the cost to construct the base is 5 dollars per square foot and the cost to construct the four sides is 3 dollars per square foot, determine

    asked on April 8, 2011
  81. 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
  82. physics

    A projectile is fired at an upward angle of 45 degrees from the top of a 265 m cliff with a speed of 350 m/s. What will be it's speed when it strikes the ground below?

    asked on October 26, 2010
  83. medicine

    How many ml of 50% dextrose should be added to 1 L of 0.9% NaCl to make a 5% dextrose solution?

    asked on September 18, 2010
  84. physics

    In a certain region of space the electric potential is V= 5x-3x^2y+2yz^2. Find the expressions for the x,y,z compenents of the electric field in this region. What is the magnitude of the field at the point P, which has coordinates 1,0,-2)m? I don't know

    asked on February 29, 2008
  85. geometry

    If KT=6 feet and LK=6.5 feet, what is the length of the radius? 6.5 feet 0.5 feet 2.5 feet 6 feet

    asked on July 14, 2020
  86. science

    Sound waves are traveling through the air. Every ½ second, the sound waves pass a detector. Which of the following choices correctly describes the period and frequency of these waves? The period is 2 s, and the frequency is 2 Hz. The frequency is ½

    asked on May 25, 2020
  87. 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
  88. math

    The master bedroom of Julie's new apartment measures 10.5 feet by 16 feet. What is the area of the room?

    asked on February 6, 2016
  89. physics

    What state of the art computer technology is used to train pilots when wanting to copy the experience of flying an aircraft?

    asked on August 30, 2015
  90. Chem 105

    A gas has a volume of 36.0 L and a pressure of 750. torr when the temperature is 10. °C. What is the pressure if the volume changes to 15.0 L and the temperature changes to 78 °C, if the amount of gas stays the same?

    asked on July 1, 2015
  91. 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
  92. Ap chem-Bases

    Calculate the pH of a 0.2M solution of Triethylamine, (C2H5)3N, with a Kb of 4.0x10^-4

    asked on February 16, 2014
  93. 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
  94. 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
  95. Math

    A car travels along a straight road, heading east for 1 h, then traveling for 30 min on another road that leads northeast. If the car has maintained a constant speed of 48 mi/h, how far is it from its starting position? Round your answer to 2 decimal

    asked on April 13, 2011
  96. calculus (integral test)

    use integral test to determine whether the series is convergent or divergent infinity (sum symbol) n=1 1/(sqrt n)^5

    asked on January 18, 2011
  97. 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
  98. physics

    The electric field in a region is given by E=ayi + axj, where a= 2V/m^2 is a constant. What is the electric potential difference between the origin and the point x= 1m, y= 2m? Do I use the formula E= - deltaV= - (V/x)i+(V/y)j+(V/z)k)?

    asked on February 28, 2008
  99. 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
  100. 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


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