# erika

Popular questions and responses by erika
1. ## Calculus

The temperature of a cup of coffee varies according to Newton's Law of Cooling: dT/dt = -k(T - A), where T is the temperature of the tea, A is the room temperature, and k is a positive constant. If the water cools from 100°C to 80°C in 1 minute at a room

2. ## calculus

The ellipse x^2+3y^3=13, has two points when x+-1 . Find the slope of the ellipse at both these points. 2. Thoroughly explain the method you used to find the slope in part 1. What are the strengths and weaknesses of the method you used? 3. Explain whether

3. ## geometry

The perimeter of triangle ABC is 13 cm. It was dilated to create triangle A'B'C' The perimeter of triangle...is cm

The distance a spring stretches varies directly with the force applied to it. If a 7-pound weight stretches a spring a distance of 24.5 inches, how far will the spring stretch if a 12-pound weight is applied?

5. ## Chemistry

How do you find the Ka1 and Ka2 of oxalic acid when it is in a solution that is 1.05 M H2C2O4 and has a pH of 0.67. [C2O4^2-] = 5.3x10^-5 M. I have tried using an ICE table for both reactions, as oxalic acid is a diprotic acid, but I am having trouble

6. ## chemistry

What effect does raising the temperature of the reaction chamber at a constant pressure have on the following reaction at equilibrium? 2NO2(g) N2O4(g) + heat A. The equilibrium shifts toward the reactants because the reverse reaction is endothermic. B. The

7. ## chemistry

Why does the density of gas in a hot air balloon decrease as the gas is heated? A. The mass of gas decreases as temperature increases. B. The mass of gas increases as temperature increases. C. The volume of gas decreases as temperature increases. D. The

8. ## calculus

Evaluate the following limit: lim x --> 2 sqrt(x^2 - x)/(2x - 3)

9. ## Chemistry

Given the following equation : 2Al+6HCl 2AlCl 3 +3H 2 If 3.00 grams of H 2 were produced, how many grams of Al reacted ? (Molar mass of Al = 26.98g / (mol) , molar mass of H 2 = 2.016 g/mol)

10. ## Chemistry

Which of the following ions is paramagnetic in the ground state: Na+ Zn+2 Ti+2 Sr+2

11. ## chemistry - 3.1.6

At a high temperature, the equilibrium constant for the decomposition of hydrogen iodide is 65.0. If the initial concentration of HI is 1.60 M, what is the concentration of hydrogen at equilibrium? 2Hl(g) H2(g) + I2(g) A. 1.42 M B. 0.753 M C. 0.240 M D.

12. ## chemistry

What is the chemical equation that describes the complete neutralization of H3PO4 by NaOH? A. H3PO4 + 2NaOH Na2HPO4 + 2H2O B. H3PO4 + H2O H2PO4- + H3O+ C. H3PO4 + NaOH NaH2PO4 + H2O D. H3PO4 + 3NaOH Na3PO4 + 3H2O

13. ## chemistry

A sample of argon at 300.°C and 50.0 atm pressure is cooled in the same container to a temperature of 0.°C. What is the new pressure?

14. ## Law

You are a health information professional closely involved with risk management at General Hospital, a teaching institution. Beginning this July, the hospital will incorporate presentations by hospital employees into its Grand Rounds series of lectures.

15. ## Maths

Let r'(t) represent the rate of growth of a dog in pounds per year. What does r(t) represent? What does integral of 2 to 6 r'(t) represent about the dog?

16. ## chemistry

How can you shift the equilibrium of the reaction between hydrogen and chlorine toward the products? H2(g) + Cl2(g) --> 2HCl(g) A. Add Cl2. B. Remove H2. C. Increase the pressure. D. Add HCl. would the answer to this one be to add Cl2? so answer A?

17. ## Math

After dinner, three friends at a restaurant paid their bill and noticed a bowl of mints on the front counter. Sean took one-third of the mints but returned four because he had a momentary pang of guilt. Fred then took one-fourth of what was left but

18. ## ela

What does aldous Huxley quote mean "Technological progress has merely provided us with more efficient means of going backward."

19. ## College Chemistry

Given 20 mL NaOH; 0.1 M, add 0.05 M HCl, 10 mL at a time. What is the pH initially of NaOH? What is the pH after adding 10 mL 0.05 M HCl? What is the pH after adding 20 mL 0.05 M HCl? What is the pH after adding 30 mL 0.05 M HCl? What is the pH after

20. ## Calculus

Find the average value of the function over [1,3] and all values of x in the interval for which the function: f(x)= 4(x^2+1)/x^2 equals its average value.

21. ## chemistry -3.2.4

Given the reaction: Cu2+(aq) + S2-(aq) CuS(s) What will happen (a) if CuSO4(aq) is added? And (b) if Na2SO4(aq) is added? A. (a) Nothing; (b) Less product will form B. (a) Less product will form; (b) Nothing C. (a) Nothing; (b) More product will form D.

22. ## chemistry

The equilibrium constant for the formation of phosphorus pentachloride is 1.9. If the partial pressure of each gas is 0.5 atm, will the reaction (as written) proceed forward or backward to reach equilibrium? PCl3(g) + Cl2(g) PCl5(g) A. Backward, because K

23. ## chemistry

How does table salt (NaCl) dissolve in water? A. Water molecules hydrogen bond with sodium ions and chloride ions. B. Each sodium ion is surrounded by chloride ions. C. Each NaCl molecule is surrounded by water molecules. D. The oxygen atoms in water

24. ## math 7th

a candle was 45 cm long .It was lit and 20% burned off .The candle went out.The next day it was lit again ,and 25% of the remaining candle burned out .then it went out On the third day the candle was lit 1/3 of the remaining amount burned off .then it went

25. ## algebra

morgan saw 10 blue cars 8 red cars and 42 white cars drive by her house in 1 hour what is the experimental probability that the next car will not be white

26. ## math

Two different relationships are shown below. Relationship 1: xy = 3 Relationship 2: A graph is shown that has the following points plotted: one comma three, two comma six, three comma nine, four comma twelve. a) Identify each relationship as direct or

27. ## CHEMISTRY

2C2H2+ 5O2-> 4CO2+ 2H20. If 1 mole of C2H2 reacts with oxygen, how many moles of C02 are produced.

28. ## Grade 9 Chemistry (2)

What is one way in which Noble Gases are different from other elements? a. Noble Gases have low boiling points b. Noble gases have high melting points c. Noble gases have extremely high densities d. Noble gases have unusually high atomic masses Also, what

29. ## chemistry

calculate the number of moles of gaseous N2 contained in a sample of 300 ml of gas saturated with water vapour at 25 degree celcius and 95 kPa.

30. ## Math

My question is: WRite the percent as a fraction and as a decimal. 0.06% I don't know how many places I need to move that decimal to convert this percent into a decimal.

31. ## Calculus

Use the Fundamental Theorem of Calculus to find the area of the region bounded by the x-axis and the graph of y = 4 x3 − 4 x. Answer: (1) Use the Fundamental Theorem of Calculus to find the average value of f(x) = e0.9 x between x = 0 and x = 2. Answer:

32. ## Calculus

Let f(x)=−2 x^3 − 3 x^2 − 2 x − 10. Find the interval where f is concave up. I Answer: < x < Find the interval where f is concave down. Answer: < x < Find the inflection point of f. Answer: x=

33. ## chemistry

Given the following reaction: 4 KO2 + 2 H2O + 4 CO2 4 KHCO3 + 3 O2 How many moles of H2O are needed to react with 12.15 moles of CO2? moles A chemical reaction occurs between solutions of LiCl and silver nitrate. This reaction produces a precipitate that

34. ## physiology

You are a physiologist on a space flight to a distant planet. You discover aliens inhabiting the planet and they are willing to submit to your tests. You discover that the aliens kidney handles the sugar alcohol mannitol just like our kidneys handle

35. ## math

Suppose you deposit \$275.00 in your savings account on December 31. Your bank pays 3 percent annual interest on savings accounts. If you do not deposit any more money into the account, what would be the balance on December 31 of the following year?

36. ## math

PLEASE TELL ME THE ANSWER TO "blank 569 divided by 6 is about 400!!!!!!!!" WHAT IS THE BLANK?!!?!?!?

37. ## Math

Know if 28 and 3 if the first number is multiple of the second

Sinx=e^y , 0

39. ## chemistry

What is a neutralization reaction? A. A reaction that involves neutral reactants B. A reaction in which the reactants are a salt and water C. A reaction in which the product is either acidic or basic D. A reaction that removes essentially all H+ and OH- I

40. ## chemistry

If the equilibrium constant is much less than 1, what can you conclude about the concentrations of the reactants and products? A. Reactants are in the numerator of the equilibrium expression, so the concentration of the reactants is high. B. Products are

41. ## chemistry

Given the reaction: Cu2+(aq) + S2-(aq) CuS(s) What will happen (a) if CuSO4(aq) is added? And (b) if Na2SO4(aq) is added? A. (a) Nothing; (b) Less product will form B. (a) Less product will form; (b) Nothing C. (a) Nothing; (b) More product will form D.

42. ## chemistry

Knowing what information would allow you to order gas molecules according to their velocity? A. Pressure and temperature B. Volume and molecular mass C. Pressure and volume D. Temperature and molecular mass

43. ## math 1

An advertiser needs a 4-inch picture of a 14 foot automobile. What is the scale factor? Write your answer in simplest form using a colon.

44. ## chemistry

How many grams do 6.2×1024 atoms of argon weigh? Answer in units of g.

45. ## Physics

A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 17.0 m/s when the hand is 1.50 m above the ground. How long is the ball in the air before it hits the ground? (The student moves her hand out of

46. ## Math

Randy had a sheep that started eating more and more as each day passed. on the first day, Tandy's sheep ate 5 carrots. On the second day, Randy's sheep ate 11 carrots. On the third day, the sheep ate 18 carrots. And on the fourth day, the gluttonous sheep

47. ## statics

A1 Helicopter in flight with unbalanced stores A helicopter in forward flight is shown in Figure 1. The helicopter in forward flight experiences a horizontal drag force DF  . The drag force DF  is assumed to pass through O. The helicopter is held up

48. ## Physics

You swing a 2.40kg stone in a circle, using the full length of a thin 60.0cm rope.

49. ## Geology

Pleistocene mammoth bone from La Brea Tar Pits of Los Angeles, California. Age: 12,200 ± 35 years

50. ## Biology 20

I'm using chromatography to identify compounds in a leaf extract for a lab, and one of the evaluation questions is 'Suggest a step that could be added to the procedure to isolate a specific compound for chemical testing.' What step could I use?

51. ## math

Jon makes a bar graph that shows the number of dogs owned by members of his class. if the smallest number is 1 and the largest number is 4; what interval should Jon use?

52. ## French

How do you translate: "May I ask some questions?" into French with correct grammar?

53. ## geometry

The angle of depression from the top of a lighthouse to a boat in the water is 30°. If the lighthouse is 89 feet tall how far is the boat from the lighthouse to the nearest foot? Answers available in ... 10Take this time to do your best on this question.

54. ## computer science C++

The variables arr1 and arr2 have been declared as pointers to integers. An array of 10 elements has been allocated, its pointer assigned to arr1, and the elements initialized to some values. Allocate an array of 20 elements, assign its pointer to arr2,

55. ## Chemistry

What is unusual about thymol blue? Why does thymbol blue change color at the pH that is does?

56. ## algebra

a steamboat travels 9 miles up a river in 3 hours and returns the same distance down the river in 2 hours. find the speed of the boat in still water and the rate of the current.

57. ## economics

Suppose that bicycles are produced by a perfectly competitive, constant cost industry. Which of the following will have a larger effect on the long-run price of bicycles: (1) a government program to advertise the health benefits of bicycling, or (2) a

58. ## math

The line y=2x + b is tangent to the graph y= sqrt x at the point P= (a,sqrt a). Find P and determine b

59. ## critical thinking

What are some other examples of paradigm in science and the field of medicine?

60. ## Chemistry

Sulfur burns in oxygen in two steps: i.S(s) + O2(g) ->SO2(g) change of Heat=-297kJ ii. 2SO2(g) + O2(g)->2SO3(g) change of heat=-198kJ Calculate the total heat released if this is the final reaction: 2S(s) + 3O2(g)->2SO3(g)

61. ## history

what date did the spanish escape from tenochtitlan and then were defeated?

62. ## Math

what is the lowest common multiple for 3, 5 and 6?

63. ## Chemistry

A system contains liquid water. The water freezes. What is the sign of q for the system for this phase change?

64. ## Science

What does a sharp shadow tell us about the way light travels?

65. ## calculus

find the equation of a quadratic function whose graph is tangent at x=1 to the line whose slope8, tangent at x=-2 to solve the line with slope-4 and tangent to the line y=-8

66. ## Science

what is the function of the alveoli in the lungs????

67. ## bilogy

methane which is composed of carbon and hydrogen, lacks !@#\$%^&tional groups and is a gas at room temperature.upon replacing one of the hydrogen atoms with a hydroxyl group, methane is converted to a liquid called methanol at room temperature. please

68. ## Calculus

Year 1960 1970 1980 1990 2000 Rate 39 59 64 89 106 of change (million people per year) Use this data to sketch a graph like that in Figure 5.2 on page 238. Draw rectangles on this graph (as in Figure 5.2) to help you underestimate the total change in the

69. ## Chemistry

What is the maximum weight (in grams) that 15 party balloons, each filled with 2 L of helium, can lift at STP? You can assume the weight of the balloon rubber is negligible and the outside air can be treated as pure nitrogen.

70. ## Calculus

Find the derivative of y = 2√s7 + 13

71. ## chemistry

A 25.0 g piece of copper at 90.0 C is placed in 100.0 g of water at 20.0 C. What is the temperature (in C) of the water once the system reaches equilibrium? The molar heat capacity of copper is 24.5 J/(mol·K).

72. ## Math

Simplify: 2xsquared minus 4xsquared

73. ## Science

What is the term that means "not able to be dissolved in a particular substance?"

74. ## Science

what is the mixture that is formed when one subtance dissolves in another called?

75. ## Science

Is rubbing alcohol a pure substance or a mixture?

76. ## Finance

Bread, Inc., has an odd dividend policy. The company has just paid a dividend of \$6 per share and has announced that it will increase the dividend by \$4 per share for each of the next five years, and then never pay another dividend. If you require an 11

77. ## philosophy

According to Renaissance philosophy, commoners often represent?

Bernice made a kite by putting 2 triangles together The base of each trangle is 9 inches The height of each triangles is 12inches and the height of each triangles is 16 inches What is the area of the kite ? show your work (hint the area of a triangle is

79. ## physiology

You are a physiologist on a space flight to a distant planet. You discover aliens inhabiting the planet and they are willing to submit to your tests. You discover that the aliens kidney handles the sugar alcohol mannitol just like our kidneys handle

80. ## math

how could you use the product 108 and 4 to find the product of 324 and 4?

81. ## chemistry

The shape of H3C+ is best described as?

82. ## calculus

Given the function y = 2 - x - x^3 Use limits to find the slope (and then the equation) of the tangent line at x = 2

83. ## Math

What is the translation rule that describes the translation A-->C?

84. ## Equal riddle

I am between 20 to 30.when u put me into 5 equal group, there is an odd number in each group and one is left over.what number am i

85. ## College Alebra

Solve the following using system of equations. The sum of three numbers is 26. The middle number numerically is one more than three times the smallest number. The largest number is two times less than five times the smallest number. Find the three numbers.

86. ## physical science

If sam drops a 40 kg mass from a height of 20 meters on earth how much was the potential energy of the mass before he dropped it a-800 j b-784 n-m c-800 n-m d-7840 j e- 200 j

87. ## physical science

a 500 kg elevator is lifted 10. How much work was done a 50 j b 50 j /kg c 5000 j d 5000 j/kg degree c

88. ## help

work is measured in which of the following units a n b n-m c m d kg m/sec /sec

89. ## help

if fred took a 40 N weight and dropped it from 10 meters. what would be the potential energy before he released it a 400j b 40 n-m c 392 n-m d 3920 j e 4000 j

90. ## science

If sam drops a 40 kg mass from a height of 20 meters on earth how much was the potential energy of the mass before he dropped it a-800 j b-784 n-m c-800 n-m d-7840 j e- 200 j

91. ## english

Help!!!!! What does the Quote "In winter I plot and plan, In spring I move" mean.

92. ## Chemistry

T/F The absorption lines of neon occur at slightly different wavelengths than its emission lines. My answer: I thought that they would have the exactly opposite wavelengths? Am I missing something?

93. ## Astronomy

T/F The absorption lines of neon occur at slightly different wavelengths than its emission lines.

94. ## Math

please if anyone could help me with this question: 1. A class paid \$20 for a cake and \$4 per child for one slice of cheese pizza. they paid \$140. how many children are in the class? 2. Rajie want to divide 24 peanuts, 64 raisins, and 56 apricots evenly

95. ## Science

The mutual gravitational attraction between two masses in space is 686 Newtons. What is the new gravitational force between these masses if the distance between them is increased by a factor of 5.6? To be graded correctly, enter the new weight in Newtons

96. ## Science

Physics A scientific instrument weighing 98 pounds on the Earth is transported to another planet whose mass is 1.7 Earth masses and whose radius is 0.7 Earth radii. What does this instrument weigh on this planet? To be graded correctly, enter the new

97. ## chem

Using the equation 2H2 + O2 ==> 2H2O, determine how many grams of water is produced when 29 moles of oxygen is consumed

98. ## chem

Using the equation 2H2 + O2 ==> 2H2O, determine how many grams of water is produced when 29 moles of oxygen is consumed

99. ## US History

4) Which of the following did not account for the development of the cattle industry in the 1870s & 1880s? a) growth of a transportation network. b) the ability to raise large herds on smaller plots of land. c) Overgrazing resulted in larger higher sale