# Alexandra

Popular questions and responses by Alexandra
1. ## ap chem

calculate the lattice enthalpy of potassium fluoride from the following data: enthalpy of formation of K(g): +89 kJ · mol−1 first ionization energy of K(g): +418 kJ · mol−1 enthalpy of formation of F(g): +79 kJ · mol−1 electron affinity of F(g):

A bottle of 12.0 M hydrochloric acid has only 35.7 mL left in it. What will the HCl concentration be if the solution is diluted to 250.0 mL?

3. ## Geometry

You are planning to use a ceramic tile design in your new bathroom. The tiles are blue-and-white equilateral triangles. You decide to arrange the blue tiles in a hexagonal shape as shown. If the side of each tile measures 7 centimeters, what will be the

4. ## chem

The reaction: 2C2H2+5O2->5O2->4CO2+2H2O is performed by mixing 175 grams of C2H2 and 175 grams of O2 to produce 127 grams of CO2 1)Limiting reagent 2)Theretical yeield of CO2 3)Percent yield of CO2

5. ## Physical Science

C(s) + H2O(g) + Heat CO(g) + H2(g) 17. How would you adjust the temperature to increase the amount of product? 18. Does the removal of hydrogen gas as it is produced shift the reaction to the left or the right? My last two questions on my homework that I

6. ## Physics

If the puck strikes the goalie's pads and stops in a distance of 4.14 cm, what average force is exerted on the pads? Answer in units of N. This is part three of three parts. 1st Part: A player strikes a hockey puck giving it a velocity of 39.486 m/s. The

7. ## physics

An object of mass 5 kg is dropped from a certain height. Just before it strikes the ground it has a kinetic energy of 1250 J. From what height was the object dropped? Ignore air resistance and use g = 10 m/s2.

8. ## AP Chemistry

If a saturated solution of Potassium Chlorate at 80 degrees celsius cools to room temperature (25 degrees celsius), how many grams of crystals form?

9. ## Physics

A 10.2 kg weather rocket generates a thrust of 200N. The rocket, pointing upward, is clamped to the top of a vertical spring. The bottom of the spring, whose spring constant is 500N/m, is anchored to the ground. a) Initially before the engine is ignited,

10. ## Chemistry

Write the formula of the corresponding acid that contains this anion. Express your answer as a chemical formula. The arsenite ion has the formula AsO33−.

11. ## Chemistry

Xe(g) + F2(g) ----uv light---> Xe F2(s) XeF2(g) + 2F2(g) ---catalyst---> XeF6(s) XeF6(s) + H2O(l) ------> Xe O3(s) + 6HF(g) Looking at these three reactions respond the following: a) For each 0.0250 grams of xenon hexaflouride that reacts, what mass of

12. ## scientist

Which is the best reason for the smaller number of drone bees compared to the number of worker bees in a beehive?

If you forget the product of 9 and 9, what can you do to figure it out?

14. ## physics

When a 2.60-kg object is hung vertically on a certain light spring described by Hooke's law, the spring stretches 2.30 cm. (a) What is the force constant of the spring? (b) If the 2.60-kg object is removed, how far will the spring stretch if a 1.30-kg

16. ## Mathematics

Find the midpoint of the line segment with end coordinates of: (−3,−1) and (−4,2) Give coordinates as decimals where appropriate.

17. ## science

1.Carbon-14 is a radioactive isotope. What is an isotope? What is the approximate half-life of carbon-14?

18. ## math

The data set below shows the number of players on each softball team in a tournament: 9 12 8 7 7 21 11 9 8 7 10 7 10 11 Which of the following statements is true based on the data set?

19. ## Physics

A large pot is placed on a stove and 1.2 kg of water at 14°C is added to the pot. The temperature of the water is raised evenly to 100°C just before it starts to boil. (a) What amount of heat is absorbed by the water in reaching 100°C? (b) The water

20. ## Physics

On Earth a fit astronaut without a space suit and life support pack can leap straight up and leave the ground with an initial vertical velocity of about v1y = 2.4 m/s and rise to a height of about h = 0.24 m above the point where he first loses contact

21. ## Physics

A cannon is fired horizontally from atop a 40.0 m tower. The cannonball travels 180 m horizontally before it strikes the ground. With what velocity did the ball leave the muzzle? Okay so this is my work for this problem. please help If I did something

22. ## Physics

Two girls decide to jump off a diving board. Katherine steps off the diving board. Anna runs straight off the diving board so that her initial velocity is solely horizontal. They both leave the diving board at the same time. Which one lands in the water

23. ## Physical Science

24. What happens when a solution of nitric acid (HNO3) is added to a solution of potassium hydroxide (KOH)? What are the products? 25. Which of the following compounds can react with H2SO4 to form a salt: NaCl, Ca(OH)2, HF, AlCl3, H2O, Mg(OH)2? Name the

24. ## chem

write the correct net ionic equation and identify spectator ions when CoSO4 and BaCL2 mix

25. ## Algebra 1

The manager of a shopping mall was asked to rope off a rectangular section of the parking lot for an automobile show. The area roped off was 250 ft by 300 ft. Post were to be placed every 25 ft around the lot. How many posts were needed? The one question I

26. ## calculus (gr 12)

Evaluate each of the following. Show all your calculations. a) f'(3) if f(x)  = x^4 − 3x b) f' (−2) if f(x) = 2x^3 + 4x^2 − 5x + 8 c) f" (1) if f(X)  = −3x^2 − 5x + 7 d)f" (−3) if f(x)  = 4x^3 −

27. ## calculus (gr 12)

Evaluate each of the following. Show all your calculations. a) f'(3) if f(x)  = x^4 − 3x b) f' (−2) if f(x) = 2x^3 + 4x^2 − 5x + 8 c) f" (1) if f(X)  = −3x^2 − 5x + 7 d)f" (−3) if f(x)  = 4x^3 −

28. ## calculus (gr 12)

Determine the velocity and acceleration as functions of time, t, for s(t) = 45t − 5t^2, where s(t) represents the distance as a function of time. (Hint: velocity and acceleration correspond to the first and second derivatives of the distance)

29. ## calculus (gr 12)

The forward motion of a space shuttle, t seconds after touchdown, is described by s(t) = 189t − t^3 , where " is measured in metres. a) What is the velocity of the shuttle at touchdown? b) How much time is required for the shuttle to stop completely? c)

30. ## calculus

Determine the maximum and minimum of each function on the given interval. a)  = 2x^3 − 9x^2 ,−2 ≤ x ≤ 4 b)  = 12x − x^3 ,  x∈ [−3,5]

31. ## physics

A 20-N horizontal force pushes an object along a rough floor so that the object moves with a constant velocity of 7.0 m/s. How much power does this force deliver to the object?

32. ## geometry

Point C is the center of the circle. Arc AB measures 5x + 2. Angle ACB measures 3x + 14. Find the value of x.

33. ## Calculus

I don't understand how to answer this problem: The base of a solid is bounded by y=x+1 and y= x^2-1. Find the volume of the solid if the cross section is perpendicular to the x axis are equilateral triangles.

34. ## Chemistry

If 10.0 grams of sodium bicarbonate reacts with 50.0mL of 2M acetic acid, what is the limiting reactant? what reactant is in excess, and by how much? What volume of carbon dioxide gas would form?

35. ## Chemistryy

what mass of silver nitrate (AgNO3) is required to prepare 400 grams of a 3.50% solution of AgNO3? Options: 1. 0.00875 g 2. 114.28 g 3. 1400 g 4. 14 g

36. ## US history

Which section of the country will be affected by the embargo of 1807?

37. ## Math

Consider the quotient, f(x)/x-h What is the remainder of this quotient? My answer- f(x-h)

38. ## English

1. What is the best summary of lines 1–16? (1 point) Alice cannot reach the doorknobs. Alice keeps shrinking until she is very tiny. She talks about being smaller than furniture in the room. She throws the Rabbit’s gloves and fan on the floor. When she

39. ## Financial math

A couple wants to lend money using the house value as a cover. The lender will lend them 70% of the value of the house. The couple bought the house 12 years ago for \$ 79,000. The house is financed by a deposit of 20% and a mortgage loan at 30 years and 12%

40. ## Math

9. Find the product. –14(8) = ? (1 point) –112 112 –108 –116 10. What is the product of –7 and –12? (1 point) –84 84 –74 74 11. Find the quotient. 36 ÷ (–3) = ? (1 point) 13 –13 –12 12 12. What is the quotient of –24 and 8? (1

41. ## Math

If the hypotenuse of a triangle is 15 yds, and one leg is 12 yds, what is the length of the other leg? Also how do you find the answer

42. ## social studies

1. la salle had conflics with which of the following groups of american indiands? hasinai caddo apache karankawa my answer is d 2. what happened when the spanish found the french colony they engaged the french settlers in warfare and killed many of them

43. ## history

Why was it smart for European colonial powers to wield power in their newly-acquired colonies through indirect rule? Can you draw parallelisms with previous dominant civilizations?

44. ## Chemistry

Initially a 1 L vessel contains 10 moles of NO2 and 6 moles of O2. At equilibrium, the vessel contains 8.8 moles of NO2. Determine Kc. Please help

45. ## Math

A ramp has been rise of 1.5 m for every 12 m of run. What is the slope of the ramp?

46. ## bio

The human egg cell above is magnified using a 10´ ocular lens and a 40´ high power objective lens. (a) Calculate the overall magnification. (b) If the field of view at high-power magnification is 400 mm, calculate the size of the field of view when the

47. ## Math

What is 3/5 of 25?

48. ## health

List sources of internal pressure and external pressure

49. ## Math

What is the probability of winning the jackpot if you play the Florida lotto? What is the probability of winning that jackpot if you play Mega Millions? What is the probability of winning the jackpot if you play Powerball?

50. ## Physics

Calculate the momentum of a bullet moving with a velocity of 1000m/s ,if it has a mass of 0.01kg

51. ## Chemistry

We did a titration lab, and one of the post-lab questions says: "the manufacturer of the vinegar used in this experiment claims that the vinegar contains 5% acetic acid by weight. Use your results and a density of 1g/mL to determine if this claim is true

52. ## science

in this experiment, 3 sets of plants were grown. one set had no light, one set had some light, one set had full sun. each set was given the same amount of water, the same temperature, the same soil and it was the same plant and same pot. in 21 days this is

53. ## math

in this experiment, 3 sets of plants were grown. one set had no light, one set had some light, one set had full sun. each set was given the same amount of water, the same temperature, the same soil and it was the same plant and same pot. in 21 days this is

54. ## College Algebra

Find all real numbers x satisfying the equation: 2^x + 3^x - 4^x + 6^x - 9^x = 1. Please help me. I really don't know what to do.

55. ## Algebra 1

I've tried so hard on this and I'm completely hopeless, can somebody help me out? Please it would mean a lot. Task 1 find the rate of change for each table, equation, or graph. How did you find the rate of change? Task 1 A. X 2 4 6 Y 10 20 30 Rate of

I need help because I don't understand how to solve this equation. 37. x/a - 1 = y/b for x So... does it mean solve for x? 39. V = 1/3 * pi * radius^2 * h for h So... does it mean solve for h? As you can see, I am really confused. Please help.

57. ## Physics Help

A circular pond of radius 12 m has a layer of ice 0.25 m thick. On a spring day, the temperature of the water below the ice is 4.0°C and the temperature of the air above is 11°C. What is the rate of heat transfer through the ice, in kW?

58. ## Physics

A circular pond of radius 12 m has a layer of ice 0.25 m thick. On a spring day, the temperature of the water below the ice is 4.0°C and the temperature of the air above is 11°C. What is the rate of heat transfer through the ice, in kW?

59. ## Physics

(c) On Earth a fit astronaut without a space suit and life support pack can leap straight up and leave the ground with an initial vertical velocity of about v1y = 2.4 m/s and rise to a height of about h = 0.24 m above the point where he first loses contact

60. ## Physics

A juggler throws a ball with an initial horizontal velocity of +1.1 m/s and an initial vertical velocity of +5.7 m/s. What is its acceleration at the top of its flight path? Make sure to consider the sign when responding. Consider the upward direction as

61. ## Physics

Your projectile launching system is partially jammed. It can only launch objects with an initial vertical velocity of 42.0 m/s, though the horizontal component of the velocity can vary. You need your projectile to land 211 m from its launch point. What

62. ## Physics

A juggler throws a ball with an initial horizontal velocity of +1.1 m/s and an initial vertical velocity of +5.7 m/s. What is its acceleration at the top of its flight path? Make sure to consider the sign when responding. Consider the upward direction as

63. ## data management

The stay at a hotel on Spring Break is normally distributed with a mean of 7 days and a standard deviation of 2 days. If 8000 people visited this hotel on Spring Break... a) If a visitor stays 6 days what is the corresponding z-score? b) How many visitors

64. ## Science

In a fetal pig, what are the 4 lobes of the brain and their functions?

"Toy Car A" is propelled by elastic force. The other forces acting on the car are gravity (pulling the car down) and friction force (between the car and the floor). What UNBALANCED forces are acting on the car? "Toy Car B" is propelled by air resistance.

66. ## Science (Balanced/Unbalanced Forces)

"Toy Car A" is propelled by elastic force. The other forces acting on the car are gravity (pulling the car down) and friction force (between the car and the floor). What UNBALANCED forces are acting on the car? "Toy Car B" is propelled by air resistance.

67. ## math

11:15 a.m. until 12:50PM WHAT IS THE ELAPSED TIME

68. ## MATH

Fabio said that there are 3 times as many people on a basketball team as on a tennis team. Is he correct? Explain why or why not.

69. ## Physical Science

Which of the following is a single replacement? a. KOH + HCl --> KCl + H2O b. 2Na + 2H2O --> H2 + 2NaOH c. 2C2H6 + 7O2 --> 4CO2 + 6H2O d. H2O + CO2 --> H2CO3 Any help would be appreciated, thank you in advance!

70. ## Algebra 1

A vending machine had to be programmed to accept any combination of nickels, dimes, and quarters that totals 40 cents. How many different combinations are possible?

71. ## chem

how many mL of .135M Sr(OH)2 are needed to neutralize 35ml of .157M HCL I know the answer came out to 20.4 ml My only question is how do I convert HCL to Sr(OH)2

72. ## vocabulary

How do you parse these words? 1. Rendition 2. Ambiguous 3. Deleterious 4. Euphemism 5. Alacrity 6. Respite 7. Polemical 8. Timorous 9. Adulation 10. Eschew

73. ## World History

How did Renaissance thinkers think the individual was defined? Explain how this idea can be compared with the value of an individual in ancient Roman and medieval European societies. Any help with this question would be greatly appreciated. Please and

74. ## algebra

The Environmental Protection Agency set a standard of 50 parts per billion of lead in drinking water. A new standard was set that safe water contains less than 15 parts per billion. a) write each of these rates as fractions using positive powers of ten. b)

State the absolute maximum value and the absolute minimum value of each function, if the function is defined on the interval shown. {I CANNOT POST THE GRAPH SO CAN SOMEONE EMAll ME AT miss.a.parker at hot mail(. com) SO I CAN EMAIL IT TO THEM SO YOU CAN

76. ## Science

Assume you can heat water with perfect insulation (all the heat from combustion of ethanol is transferred to water). What is the volume of ethanol required to heat 100 mL of water by 10 degrees C? (You will need to look up density of ethanol, specific heat

77. ## statistics

. A certain researcher thinks that the proportion of women who say that female bosses are harshly critical is greater than the proportion of men. In a random sample of 200 women, 27% said that female bosses are harshly critical. In a random sample of 220

78. ## physics

A 16.0-N weight slides down a rough inclined plane that makes an angle of 28.0° with the horizontal. The weight, which started from rest, gains a speed of 15.0 m/s after sliding 150 m. How much work is done against friction?

79. ## Exploring Multiplication

how can you find out how many slices your class needs if each pizza has 8 slices and ther are 28 kids?

80. ## Chemistry

If the concentration of a reactant is decreased, will the speed of the reaction increase or decrease? Explain. I understand that if the concentration of a reactant is INCREASED, the frequency of coliision increases, making the rate of reaction increase.

81. ## Chemistry

So I do know how to work out letter a) but I'm still very confused with parts b and c. Appreciate the help! 2FeN(s) + 3H2(g) --> 2Fe(s) + 2NH3(g) Suppose that the reaction is carried out at 300C and 3.00 atm. 1.00 grams of iron (III) nitride reacts. a)What

82. ## Desert

How are deflation hollows made? Could you also give me some more pictures of hoodoos (the landforms)?

83. ## math

A green purse costs \$11, which is 11 times as much as a red tie costs. How much does the red tie cost?

84. ## math

To solve for the following proportion, you could use equivalent ratios, divide out the known ratio, or use cross products. Choose one of these methods to solve for t. Show your work and explain why you chose that method. 18/5 = 4/t

85. ## math

A plane flying with a constant speed of 14 km/min passes over a ground radar station at an altitude of 7 km and climbs at an angle of 35 degrees. At what rate, in km/min, is the distance from the plane to the radar station increasing 5 minutes later?

86. ## Calculus

The base of a solid is bounded by y=2sqrtx, y=2 and x=4. Find the volume of solid if cross sections perpendicular to y=2 are semicircles

87. ## Chemistry

How many moles of acetic acid are there in 25 mL container?

88. ## phoenix

The library is an excellent sources and option. What are some other public option? examples & explanation.

89. ## statistics

Assume the IQ's of men and women can be described by a Normal model with a mean of 100 and a standard deviation of 15. For the first part: What percent of people do you expect to have IQ's over 120?

90. ## Algebra

A candy cane 30 cm high has a circumference of 3 cm. The red “ribbon” makes exactly 4 complete turns round the candy cane while its two ends touch the cane's top and bottom. How long is the ribbon in cm? It doesn't make any sense to me. Can somebody

how do you do rate of change?

92. ## college alg help!

cannot figure a way to do this problem: An investment of \$98,000 was made by a business club. The investment was split into three parts and lasted for one year. The first part of the investment earned 8% interest, the second 6%, and third 9%. The total

93. ## Chemistry

In the study of biochemical processes, a common buffering agent is the weak base trishydroxymethylaminomethane, often abbreviated as Tris. At 25 C, Tris has a pKb of 5.91. The hydrochloride can be abbreviated as Tris HCl. What volume of 10.0 M NaOH is

Can you simplify 9 over 16?

95. ## chemistry

what is the density of 700 ml of a gas that has a mass of 7 g?

96. ## chemistry

how many joules are formed when 3 moles oh CH4(g) react?

97. ## Chemistry

A gas storage tank has a volume of 3.5*10^5 m^3 when the temperature is 27 degrees celcius and the pressure is 101 kPa. What is the new volume of the tank if the temperature drops to -10 degrees celcius and the pressure drops to 95 kPa?

98. ## math

The quotient of two numbers is 8. The sum of the same two numbers is 72. What is the two numbers

99. ## college physics

Let's say that you find a slope of 6.671×10-14 for square plates of width 11.5 cm. What do you get for the value of the permittivity of free space?