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

    asked on July 24, 2009
  2. Physics

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

    asked on February 9, 2009
  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?

    asked on July 7, 2009
  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

    asked on March 4, 2014
  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

    asked on November 18, 2013
  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

    asked on July 15, 2020
  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.

    asked on April 11, 2010
  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

    asked on July 24, 2009
  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 =

    asked on April 17, 2009
  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 ==>

    asked on November 16, 2010
  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

    asked on February 3, 2016
  12. MATH


    asked on September 30, 2014
  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

    asked on November 18, 2013
  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?

    asked on December 5, 2012
  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?

    asked on December 5, 2012
  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

    asked on September 26, 2010
  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

    asked on April 17, 2009
  18. Simple

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

    asked on February 17, 2009
  19. world history

    How has the global economy changed after the Cold War?

    asked on April 19, 2014
  20. Chemistry

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

    asked on October 19, 2015
  21. Madison

    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)

    asked on March 26, 2015
  22. Hypoventilation VS Bradyapnea

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

    asked on March 24, 2011
  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?

    asked on March 13, 2009
  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

    asked on December 12, 2008
  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

    asked on May 11, 2008

    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?

    asked on October 18, 2012
  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?

    asked on October 17, 2012
  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

    asked on April 3, 2012
  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

    asked on March 30, 2011
  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

    asked on March 3, 2011
  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)?

    asked on January 2, 2011
  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:

    asked on November 14, 2010
  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

    asked on September 26, 2010
  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

    asked on July 27, 2009
  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 =

    asked on July 23, 2009
  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

    asked on July 7, 2009
  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

    asked on April 2, 2009
  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

    asked on January 22, 2009
  39. Biology

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

    asked on November 25, 2008
  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

    asked on September 23, 2008
  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

    asked on September 23, 2008
  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

    asked on September 23, 2008
  43. English

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

    asked on February 28, 2008
  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

    asked on September 20, 2007
  45. Maths

    Give three different ways of partitioning 775 answer

    asked on October 6, 2019
  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.

    asked on May 27, 2019
  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

    asked on March 5, 2015
  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

    asked on January 8, 2015
  49. physics

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

    asked on September 13, 2014
  50. social studies

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

    asked on April 23, 2014
  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

    asked on April 19, 2014
  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"?

    asked on August 29, 2013
  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

    asked on December 5, 2012
  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

    asked on October 18, 2012

    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?

    asked on October 18, 2012
  56. CHEM

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

    asked on October 18, 2012
  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

    asked on October 27, 2011
  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

    asked on May 31, 2011
  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:

    asked on March 24, 2011
  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

    asked on March 3, 2011
  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

    asked on February 27, 2011
  62. Math/Radioactive Dating

    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

    asked on February 19, 2011
  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

    asked on November 28, 2010
  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?

    asked on March 29, 2011
  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.

    asked on August 1, 2010
  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

    asked on April 11, 2010
  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

    asked on April 11, 2010
  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?

    asked on March 30, 2010
  69. bio

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

    asked on March 9, 2010
  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.

    asked on February 28, 2010
  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!!!

    asked on February 28, 2010
  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?

    asked on February 28, 2010
  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

    asked on February 28, 2010
  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?

    asked on February 21, 2010
  75. psychology of health

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

    asked on January 25, 2010
  76. Bio

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

    asked on December 9, 2009
  77. Bio

    What do insulin injections do for people with diabetes?

    asked on December 8, 2009
  78. English

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

    asked on December 6, 2009

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

    asked on November 12, 2009
  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!

    asked on November 5, 2009
  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

    asked on September 26, 2009
  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?

    asked on September 24, 2009
  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

    asked on July 27, 2009
  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?

    asked on July 26, 2009
  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?

    asked on July 25, 2009
  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:

    asked on July 19, 2009
  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

    asked on July 8, 2009
  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

    asked on July 6, 2009
  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

    asked on June 7, 2009
  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

    asked on May 6, 2009
  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

    asked on April 26, 2009
  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?

    asked on April 21, 2009

    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

    asked on April 9, 2009
  94. Chem

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

    asked on April 6, 2009
  95. chem

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

    asked on March 13, 2009
  96. Markovnikov's Rule

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

    asked on March 12, 2009
  97. chem

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

    asked on March 12, 2009
  98. English

    Does this line make sense: something good comes of everything

    asked on February 5, 2009
  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.

    asked on January 24, 2009
  100. Bicarbonate

    The stomach secetes bicarbonate into the small intestine. Does the stomach secrete the bicarbonte into the duodenum? And if so, what does the bicarbonate go through to get to the duodenum?

    asked on November 25, 2008


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