# Lena

Popular questions and responses by Lena
1. ## CHEM

A concentrated weak acid is best described as which of the following? (a) a solution with a high pH (b) a solution where the concentration of undissociated acid particles is high and relative quantity of hydronium ions is low (c) a solution where the

2. ## Physics

How is Snell's law being used in real life application?

3. ## Chem

What 4 quantum numbers describes one of the outermost electrons in a strontium atom in ground state? 5,0,0,1/2 Is my answer correct?

4. ## Chemistry

what volume of concentrated 18M H2SO4 is required to prepare 250mL of a 6.0M solution? how would you solve this problem? i know it has something to do with the molarity formula but no idea how to apply it

5. ## physics

a 1.2 kg cart slides eastward down a frictionless ramp from a height of 1.8 m and then onto a horizontal surface where it has a head-on elastic collision with a stationary 2.0 kg cart cushioned by an ideal Hooke's law spring. the maximum compression of the

6. ## physics

Each satellite in the Global Positioning System travels at 1.05 x 10^4 km/h. Determine, in kilometres, each satellite’s (a) orbital radius and (b) distance from the surface of Earth. I did r = (Gm)/v^2 and got 1.37 x 10^8 km for (a), but the answers are

7. ## Physics

The range of human hearing extends from approximately 20 Hz to 20000 Hz. Find the wavelength of these extremes when the speed of sound in air is equal to 343 m/s.

8. ## chem

Calculate the pH of 0.20 M NaCN solution. NaCN ---> Na+ + CN- CN- + H20+ ---> HCN+ + OH- Initial conc. of CN- = 0.20 mol/L change = -x equillibrium = 0.20-x HCN equill. = +x OH equill. = 1x10^-7+x Ka= 6.2 x 10^-10 Kb = KW/Ka = 1x10^-14/6n2 x 10^-10 = 1.6 x

9. ## Friction

A 200kg crate us pushed horizontally with a force of 700 N. If the coefficient of friction is 0.20, calculate the acceleratio of the crate. I tried doing this but I don't seem to be getting the right answer. m = 200 kg f(app)= 700 N U = 0.20 Ff =

10. ## Chemistry

A student did the Synthesis of Salicylic Acid experiment starting with 3.89 g of methyl salicylate (C8H8O3) and using 40 mL of 6.0 M NaOH. To evaluate her success she needs to determine the limiting reagent. The reaction goes as follows: C8H8O3 + H2O ==>

11. ## math

Scientists are conducting an experiment with a gas in a sealed container. The mass of the gas is measured, and the scientists realize that the gas is leaking over time in a linear way. Six minutes since the experiment started, the gas had a mass of 144

12. ## MATH

SASHA AND FRANCISCO WERE SELLING LEMONADE FOR \$.25 PER HALF CUP AND \$.50 PER FULL CUP. AT THE END OF THE DAY THEY HAD COLLECTED \$15 AND HAD USED 37 CUPS. HOW MANY FULL CUPS AND HOW MANY HALF CUPS DID THEY SELL?

13. ## Physics

In a demonstration in physics class, a 1.2 kg dynamics cart starts from rest at the top of a ramp. the ramp is 2.4 m above the ground. the cart then rolls down to the bottom of the ramp, where it collides with a stationary 1.4 kg dynamics cart. Assume that

14. ## chemistry

Methane (CH4) burns in oxygen to produce carbon dioxide and water vapor. The balanced equation is: CH4 + 2 O2 -> CO2 + 2 H2O What volume of carbon dioxide is produced when 3.2 L of oxygen are consumed?

15. ## chemistry

Methane (CH4) burns in oxygen to produce carbon dioxide and water vapor. The balanced equation is: CH4 + 2 O2 -> CO2 + 2 H2O What volume of carbon dioxide is produced when 3.2 L of oxygen are consumed?

16. ## Biology

The type of cartilage associated with bone function and development is what? I know that the elastic cartilage contains elastin which allows for elasticity and maintains shape of certain structures. Fibro is strong and rigid (strongest of 3) Hyaline

17. ## Physics

You are driving 2500 Kg car at a constant speed of 14 m/s along an icy, but stright and lvel road. While approaching a traffic light, it turns red. You slam on the brakes. You wheels lock, the tires begin skidding and the car slides to a halt in a distance

18. ## Simple

is the image that a magnifying glass produces real or virtual and how do you figure that out?

19. ## world history

How has the global economy changed after the Cold War?

20. ## Chemistry

Why does the temperature in exothermic reactions increase, reach a maximum, and then decrease?

Elliot put 7 cups of tea into the pitcher shown. How many more cups of tea does he need to fill the pitcher? (1 quart = 4 cups)

Hypoventilation VS Bradyapnea What's the difference b/t the two? Aren't they both decreased breathing rate?

23. ## chem

how would I do the elimination reaction of 2-chloropentane. When I figured it out I got the products as being 1-pentene and hydrogen chloride. Is this correct?

24. ## Chem

I had a question that said would butane sink to the floor or rise to the ceiling in air. I would say sink to the floor but I was googling this and several sites said it wouldn't completely sink and that it would float. Is this right? And if so how would I

25. ## English; grammar

Could you please tell me if I have properly identified the part of speech of each word. If I have made a mistake, could you please correct me. - Word: femurs Sentance:Jawbones, hipbones, femurs. Part of Speech:NOUN Word: Apache Sentance: White smoke puffed

26. ## CHEMISTRY

What element is represented by this electron ground state configuration : [Kr] 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d2 7s2 Is this really Krypton?

27. ## Chem help

Answer the questions below for an element that has the electron configuration 1s2 2s2 2p6 3s2 3p6 4s1. A. What is the symbol for this element? B. What is the atomic number of this element? C. How many unpaired electrons does an atom of this elelemt have?

28. ## Chemistry

in the presence of NH3, Cu+2 forms the complex ion [Cu(NH3)4]+2. If the equilibrium concentrations of Cu+2 and [Cu(NH3)4]+2 are 1.8x10^-17M and 1.0x10^-3M respectively, in a 1.5 M NH3 solution, calculate the value for the overall formation constant of

29. ## chemistry

A studen is asket to calculate the amount of heat involved in changing 10.0 g of liquid bomine at room temperature (22.5 C) to vapor at 59.0 C. To do this, one must know specific heat (0.474 J/g*C), boiling point (59 C), and heat of vaporization (29.6

30. ## Peptide Bonds

Which of the following shows linear sequence of atoms joined by covalent bonds in peptide backbone. a) -N-C-C-N-C-C-N b) -N-C-O-N-C-O- c) -N-C-C-O-N-C-C-O d)-N-H-C-C-N-H-C-C The answer is a). Is that because it's the only one that linear; as in it doesn't

31. ## calculus ap

what is the slope of the line tangent to the curve y^3+x^2y^2-3x^3=9 at the point (1,2)?

32. ## Calculus

Oil is leaking out of a ruptured tanker at a rate of r = 19e^(2t) gallons per hour. Write a definite integral that represents the total quantity of oil which leaks out of the tanker in the first 3 hours. Using your formula answer the following questions:

33. ## Bio

The type of cartilage associated with bone function and development is what? I know that the elastic cartilage contains elastin which allows for elasticity and maintains shape of certain structures. Fibro is strong and rigid (strongest of 3) Hyaline

34. ## Chem

Co2(g) ---> CO2(l) + heat This equation was given to me and asked why high pressure was needed to keep carbon dioxide in the liquid state. With the information given; I don't exactly know how to answer the question. How do you increase the pressure of a

35. ## Chem

Methylaime, CH3NH2. If a 0.100 mol/L solution of methyamine has a pH of 11.80, calculate the ionization constant for the weak base. What is an ionization constant. Is it just K? This is what I did so far: 11.80 = -log (concentration of h3o+) 10^-11.80 =

36. ## Chem

I was asked to fraw the energy level diagram for carbon. Carbon has 6 electrons so would the 2s and 2p orbitals both be half full? 1s = 2 electrons 2s= 1 electron 2p = 3 electrons

37. ## Physics

How does mass effect a free falling object? I was thinking that if the mass is greater then object would have a higher acceleration because due to it's weight it would have less drag on it from the air. Something of that sort. Could someone else this to me

38. ## CHEM

I don't understand how to find the formula of a hydrate. Here's one of the question. if you guide me through it I think I'll be able to do the rest of them. Thanks :) When 100g of ZnSO4xœH2O is heated, 43.86g of water is given off. Calculate the formula

39. ## Biology

What is pancreatic amylase. I seem to find every kind of amylase except pancreatic. I need a good, understandable definition. Thanks.

40. ## science

so would it be better to place a wilted flower in tap water or distilled water? Answer: I would say distilled water because it contains a lower cocnentration of solute than the flower and therefore the water would more easily diffuse into the flower. Tap

41. ## SCI

Hypothetically speaking, I placed a cell in a glass of water and after about a day the cell grew in size. Why did the cell grow? Well I was thinking this: The reason the cell grew was because there was a higher concentration of water outside of the cell

42. ## bob -sci.

keeping osmosis in mind, would it be better to soak wilted flowers in distilled water or normal tap water? I was thinking tap but I`m not sure why I`m thinking that. Maybe because tap water has a higher solute concentration that than distilled. i`m not

43. ## English

whats the word that means your not lying but not telling the truth. like not telling the whole truth

44. ## Organic Chemistry/Biology

My text has a review of some chemistry before getting into the biology bit. I have come to a question "what are 3 characteristics/features of an organic compound." My book seems to only have the general they all have carbon. The rest goes into depth about

45. ## Maths

Give three different ways of partitioning 775 answer

46. ## Chemistry

Calculate the pOH of a 15 mL sample of 0.76 mol/L hydrosulfuric acid given that it only dissosiates 92% in solution.

47. ## Physic

You are moving into an apartment and take the elevator to the 6th floor. Suppose your weight is 640 N and that of your belongings is 940 N. (a) Determine the work done by the elevator in lifting you and your belongings up to the 6th floor (15.2 m) at a

48. ## Chemistry

In an experiment, you dissolve 0.30 g of KHP (MM = 204.22 g/mol) in 20 mL of DI water and titrate the sample with 0.10 M NaOH. Calculate the volume (to the nearest mL) of NaOH required to reach the equivalence point. IS it a) 3 b)15 c)20 d)30 e)100 I have

49. ## physics

if the diamter of a human hair is (50*10^-6 m) estimate the volume of hair on your head

50. ## social studies

What major land form and body of water cover much of northern south america?

51. ## Physics

The inner and outer surfaces of a cell membrane carry a negative and positive charge, respectively. Because of these charges, a potential difference of about 0.070 V exists across the membrane. The thickness of the membrane is 0.000000008 m. What is the

52. ## world history

1. How does the story of Coca-Cola relate to the rise of capitalism and entrepreneurship in the 19th and early 20th c? 2. what is the "iron curtain"?

53. ## Determination of ASA Content of Tablets Lab Report

Not asking for answers necesarily but I would to know how to approach each question Mass of pure acetylsalicylic acid (ASA) : .508 g Dilution Absorbance (a.u.) 2:11 .116 4:11 .259 6:11 .392 8:11 .502 10:11 .548 Mass of tablet : .380 g Absorbance read on

54. ## CHEM

Silicon carbide, commonly known as carborundum, is a very hard and abrasive substance. The compound is prepared by heating silicon dioxide in the presence of graphitic carbon: SiO2(s) + 2C(s) --> SiC(s) + CO2(g) How many grams of silicon carbide can be

55. ## CHEMISTRY

What element is represented by this electron ground state configuration : [Kr] 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d2 7s2 Is this really Krypton?

56. ## CHEM

Arrange the following in order of increasing atomic radii from smallest to largest. Mg Ra Sr Be Ca Ba

57. ## Math

Mathman couldn't resist the grooving tunes inside and paid his \$5.00. He was heading straight for the punch bowl when he noticed a witch mixing it together using a solution which was 60% lizard drool and another that was only 25% lizard drool. If she

58. ## microeconomics

TRUE OR FALSE: 9. Assume that the Minimum Wage has increased to \$14 from \$10. If the total labour-income at the wage of \$14 is higher than the total labour-income at the wage of \$10, it means that the labour-demand with respect to wage is elastic. FALSE. I

59. ## Nutrition (Blood Tests)

If there was an eight year old boy who wasn't get enough to eat and was not eating nutritious foods, what kinds of things would be wrong with him? What things would be wrong in his blood tests? This is what I'm thinking: - prolonged hunger - depression:

60. ## Hydrogen bonding with polypeptides

In a polypeptide at physiologic pH, hydrogen bonding may form between which of the following? a) side chains of leucine residue and lysine residue b) side chains of aspartyl residue and glutamyl residue c) terminal amino acid group and terminal carboxyl

61. ## Biochem - Diabetes

Type 1 diabetic injected insufficient insulin so her body can’t use glucose in blood. Blood glucose is 38 mM (normal value = 3.3-5.8 mM). To adjust osmolality, she increased urine output = dehydration. Should she be treated with water? The answer is NO

My teacher said that if the ratio of mass (in a rock) for 40K and 40Ar was 1:3 then the age of the rock would be 2.5 billion years. I don't understand how he concluded that to be the age. The only thing he knew was that the half-life of K40 = 1.25 billion

63. ## Chemistry

How many milliliters of 0.710 M HCl are required to react with 47.80 grams of CaCO3 ? Given the balanced reaction equation: 6 FeCl2(aq) + K2Cr2O7(aq) + 14 HCl(aq) 6 FeCl3(aq) + 2 CrCl3(aq) + 2 KCl(aq) + 7 H2O(l) How many moles of FeCl2(aq) are required to

64. ## Primary Auditory Cortex (Psych)

In lecture the prof says A1 and primary visual cortex interchangeably. Are they the two just different ways of referring to the same thing or is A1 a specific regions in the primary auditory cortex?

65. ## Laptops

I've been searching a ton of websites but I can't seem to find a proper answer. I'm a first-year Nursing student and I need an opnion on what laptop would best suit me based on my course. Thanks in advance.

66. ## The Heart

What is the relationship between fitness level and recovery HR after sub-maximal exercise? I was thinking the more fit you are, the faster your HR will drop back to what it is when you're resting. If you're unfit, it'll take longer for that HR to go down

67. ## Anatomy (The Heart)

What is the relationship between fitness level and recovery HR after sub-maximal exercise? I was thinking the more fit you are, the faster your HR will drop back to what it is when you're resting. If you're unfit, it'll take longer for that HR to go down

68. ## Digestive System

Pancreatic beta cells release insulin into the blood and INHIBIT the pancreatic alpha cells from secreting glucogon. What does inhibit mean in this context and is the insulin inhibiting or is it the beta cells?

69. ## bio

is hydrogenated margarine a trans fat? is butter a saturated fat?

70. ## history

What place did the Israeli Olympic Team visit in the days prior to the hostage taking? I'm thinking it was a memorial of a concentration camp. I'm not too sure.

71. ## algebra

Solve the following equation: k2 + 4k = 0 By factoring and By using the quadratic formula Can someone please help me to understand how to this problem...I do not understand the steps to get the correct answer. Thanks!!!

72. ## History

What had occurred 40 years prior to the Munich Olympics which made the games so important? The only things I got are the Holocaust, the separation of Israel and Palestine and WW2. Is there anything else that was major?

73. ## History

why were the munich olympic games viewed as being of particular importance world politics, national relations, and reconciliation with the Jewish people? I think the Holocaust occured before that and Germany wanted to prove that they were moving forward

74. ## careers

What part of food science does the career of sous chef fall under? Options: preparation, utilization, evaluation,production I was thinking preparation because you're a chef but sous chef also make menus so what would that go under?

75. ## psychology of health

Has specialized medicine made a positive impact on the quality of patient health care delivery?

76. ## Bio

If you don't have a functioning corpus luteum, does that mean no ovulation takes place?

77. ## Bio

What do insulin injections do for people with diabetes?

78. ## English

Do these words mean the exact same thing? Sexism, Chauvinism

79. ## ENGLISH

In the Handmaid's Tale by Margret Atwood, does the Handmaid system actually repopulate the state?

80. ## Math

Conner estimated that the radius of one of the circles on the playground was 2 yards. If Conner was correct then: a. the radius was how many feet? b. the diameter was how many feet? Thanks!

81. ## The Excavation : By Augusto Roa Bastos

I read this short story and I understand it pretty much but there are some things Im confused about. Were all the people in Cell 5 murdered by machine gun fire? Did Perucho Rodi escape from Cell 4 and avoid getting caught as one of the people involved? Was

82. ## Science

When we look at a leaf, we see the colors of light that are reflected off its surface. How does this explain there relatively low flow of oxygen in green light?

83. ## pH calculations

A backyard pool as a pH of 7.4. At this level, the concentrations of hypochlorus acid and hypochlorite are approximetly equal. HClO(aq) H^+ (aq) + ClO^- (aq) (a) Predict the effect of increasing pH has on the concentration of HClO(aq) in the pool. For this

84. ## Chem

When you have carbon monoxide poisoning and you put on a 100% oxygen mask, will the CO react with the O to make CO2 which the body will exhale?

85. ## Chem

An air purifiction system involving litium hydroxide, LiOH, was used. LiOH absorbs carbon dioxide. 2LiOH(s) + CO2(g) Li2CO3(s) + H2O(l) Use Le Chatelier's principle to explain why the amount of time astronauts can spend in a space-craft is limited?

86. ## Chemistry

Initially, 1.68 mol of PCl5(g) and 0.36 mol of PCl3(g) are in mixed in a 2.00 l container. It is later found that 1.44 mol of PCl5 are present when the system has reached equillibrium. Calculate the value of the equllibrium. This is what I did: Equation:

87. ## Chem

There is this one question that akss for the sum of bond dipoles. I don't understand that at all. What is the question asking? I thought I was figuring out if the difference between the dipoles and if I got a 0 then the molecule would be non-polar and if I

88. ## Chem

How many moles of hydrogen and oxygen are in 2 moles of water? water: h2o # of molecules = (6.022 x 10^23)(2)= 1.2044 x 10^23 # of hydrogen atoms = (1.2044 x 10^23)(2)= 2.4088 x 10^24 # of oxygen atoms = 1.2044 x 10^24 Did I do this correctly? What do I do

89. ## Math

I don't think I am understanding this question. Question: A zoo started with 16 cranes and panned to hatch 20 chicks. A few birds were kept for breeding and the rest realeased into the wild. At the end of last year, a total of 136 cranes had spent some

90. ## Shakespeare

How would I use ellipses in Shakspearean quotes? I know that after every line you put a / but I want to omit like half a speech and get to the end. How would I do this? This is what I want to use: “You call me misbeliever, cutthroat dog/ And you spit

91. ## Physics

Im talking about the friction between a golf club and the air as the golf club is swinging towards the ball. how does the mass of the club, the velocity of the swing and the acceleration affect the friction acting on the club and how much will it slow

92. ## English

I need a more formal word or phrase for saying "beat up." My sentance is something like 'he beat him up' but i`m writing a formal piece so I need to substitute the phrase for something more formal. Any ideas?

93. ## ENEGRY COSTS

I need to know how much it would cost to build the following plants (as in factories): Solar energy plant Biomass plant Geothermal energy plant Wind energy plant nuclear Energy plant

94. ## Chem

NaOH (s) + H2O (l) -----> NaOH (aq) I`m having a hard time balancing this. Can you even balance this?

95. ## chem

for the equation: propane + bromine how do I know on which carbon the Br would attatch itself to.

96. ## Markovnikov's Rule

What if both carbon's have the same number of hydrogens, then which carbon gets "richer" in hydrogens?

97. ## chem

Br | CH3 - CH2 - CH - CH - CH2 -CH3 | CH2CH3 How would I name the structure above? Would it be 3-bromo-3-methylpentane?

98. ## English

Does this line make sense: something good comes of everything

99. ## Biology

How is sex (gender) determined in mammals? I was thinking that if the male gave over an X chromosome that the baby would for sure be a male because males have XY and if the male gave over an X then baby would for sure be a female because all females ar XY.