# Questions Asked onMarch 20, 2013

1. ## Chemistry

Which of the following pairs would make a good buffer solution in an aqueous solution? A) H2SO4 and NaHSO4 B) Ca(NO3)2 and HNO3 C) HCl and NaCl D) HF and NaOH E) none of them I know the answer is D but I don't understand why. I would think it would be C

2. ## Physics

A layer of oil (n = 1.45) floats on an unknown liquid. A ray of light originates in the oil and passes into the unknown liquid. The angle of incidence is 64.8 degrees, and the angle of refraction is 68.0 degrees. What is the index of refraction of the

3. ## Pre-Algebra

1. What data are represented by the stem-and-leaf plot below? 3 | 7 8 9 4 | 1 3 7 5 | 2 4 Key: 4 | 1 means 41 a. 37, 38, 39, 41, 43, 47, 52, 54 b. 73, 83, 93, 14, 34, 74, 25, 45 c. 7, 8, 9, 1, 3, 7, 2, 4 d. 37, 38, 39, 14, 34, 74, 25, 45 2. Find the mode

4. ## calculus

1. The radius of a sphere is r inches at time t seconds. Find the radius when the rates of increase of the surface area and the radius are numerically equal. A 1/4π in B 1/5π in C 1/3π in D 1/8π in E 1/2π in

5. ## maths

solve 2x+3y=13 with 4x+5y=23

48. ## Chemistry

Consider the reaction CO3^-2+H2OHCO3^+OH^-. Kb for CO3^-2 is 2.1x10^-4 at 25 Celsius . What is Ka for the HCO3^- ion at 25 Celsius?

49. ## Chemistry

A 5.0-g Sample of KBr at 25.0 degrees celsius dissolves 25.0 mL of water also at 25.0 degrees celsius. The final equilibrium temperature of the resulting soltution is 18.1 degrees celsius. What is the enthalpy of of solution in kilojoules per mole of KBr?

50. ## chemistry

CuSO4+4NH3-Cu(NH3)4SO4 a. if you use 10.0g 0f CuSO4 and excess NH3, What is the theoretical yield of Cu(NH3)4SO4? b. if you produce 12.6g of Cu(NH3)4SO4, What is the percent yield of the compund?

51. ## chemistry

How many grams of Mg(OH)2 are needed to neutralize 55 ml of 0.25 M HCl . according to the following reaction. (show all calculations for credit) Mg(OH)2 (aq) + 2HCl(aq) --- MgCl2 (aq) + 2H2O(l)

52. ## Physics

Heat flow question help?A brass rod with a length of 30.0 cm is placed side by side with an aluminum rod with a length of 30.0 cm and this system is placed between a hot temperature of 100°C and a cold temperature of 10.0°C. The coefficient of thermal

53. ## Physics

A) With what minimum speed must you toss a 190 g ball straight up to hit the 15.0 m-high roof of the gymnasium if you release the ball 1.70 m above the ground? Solve this problem using energy. B) With what speed does the ball hit the ground?

54. ## Physics Heat

1) While Laurie is boiling water to cook spaghetti, the phone rings, and all 1.5 kg of water boils away during her conversation.If the water was initially at 15℃, how much heat must have been gained for all of it to turn into a water vapor? 2)By January,

55. ## CHEMISTRY

1. What is the vapor pressure at 25°C of a solution of 1.20g of nephtalene C10H8 in 25.6g of benzone C6H6? The vapor pressure of pure benzene at 23°C is 86.0mmHg the vapor pressure of naphthalene can be neglected. Calculate the vapor pressure lowering of

56. ## Critical Points, Etc.

find the values for a, b, and c such that the function f(x)= x^3 + ax^2 + bx+ c has a critical point at (1,5) and an inflection point at (2,3). a= -6 b= 3 c= 7 i got those, but they're wrong. i'm not sure why. :/

57. ## Chemistry

Repost:: sorry couldn't understand it What is the concentration of C2O4^-2 in a 0.370M oxalic acid solution? Ka1=5.6x10^-2 and Ka2=5.1x10^-5

58. ## chemestiry

Al2(SO4)3(aq) + BaCl2(aq) BaSO4(s) + AlCl3(aq) Consider the unbalanced equation above. A 0.680 g sample of impure Al2(SO4)3 reacts with excess BaCl2. If the sample produces 0.530 g of BaSO4, what is the mass percent of Al2(SO4)3 in the sample?

59. ## chemestiry

Al2(SO4)3(aq) + BaCl2(aq) BaSO4(s) + AlCl3(aq) Consider the unbalanced equation above. A 0.680 g sample of impure Al2(SO4)3 reacts with excess BaCl2. If the sample produces 0.530 g of BaSO4, what is the mass percent of Al2(SO4)3 in the sample?

60. ## science

How do organs relate to cells and tissues?

82. ## Physics

A small block of mass m slides along the frictionless loop track,if it starts from rest at point p,what us the resultant force acting on it at q?

83. ## math

give an example of a situation that has 8 different outcomes

84. ## Math

Im helping my son to find the area of a rectangle that is 7 3/8 inches and 4 inches the height. I need to know how to convert the fraction into a whole number.

85. ## chemistry

Nitric acid can be prepared from ammonia by the following steps; 4nh3 + 5o2 = 6h2o + 4no 2no + O2 = 2no2 2no2 + h2o = hno3 + hno2 3hno2 = hno3 + 2no + h2o If all the steps take place consecutively, completely and without recycling, what mass of ammonia is

86. ## Chemistry

If you add 100 g of salt to 5 Kg of cooking water, how will it effect the boiling point? (molar mass of NaCl 58.5 g, Kbwater=0.51 degrees/m)

87. ## English

choose from For example or therefore 1. Most listeners don't simply absord your message of thier own called feedback._______, when you phone a friend to say you'll be late, you may hear,"Hey, you really need to get here on time!" That is feedback. I am a

170. ## Physics

If a vehicle starts at 31 km/h and only travels 4.7m in 1.1 seconds due to deceleration, how fast is it going after 1.1 seconds?

171. ## maths-probabilty

Bag 1 contains 2 white and 3 red balls and bag 2 contains 4 white and 5 red balls. 1 ball is drawn at random from one of the bags and is found to be red. Find the probability that it was drawn from bag 2

172. ## Math

Can you completely cover a 4 ft by 8 ft area with 3 ft by 3 ft tiles without cutting the tiles?

173. ## Math

Can you completely cover a 4 ft by 8 ft area with 3 ft by 3 ft tiles without cutting the tiles?

174. ## economics

demand funtion for a commodity is=12-3p.

175. ## trig

Sandra wants to find the height of a moutain. From her first location on the ground, she finds the angle of elevation to the top of the mountain to be 35 degrees 15 minutes. After moving 1000 meters closer to the moutain on level ground, she finds the

176. ## Physics

A) With what minimum speed must you toss a 190 ball straight up to hit the 15.0 -high roof of the gymnasium if you release the ball 1.70 above the ground? Solve this problem using energy. B) With what speed does the ball hit the ground?

177. ## Physics

A rectangular conducting homogeneous (which means the material is the same throughout) block has dimensions 1cm x 2cm x 3cm . A voltage V is applied between all opposite faces of the block and the corresponding currents were recorded. What is the maximum

178. ## English

Word box left compact earmark frigid intensive scant strident titanic 4.When the winds begin to turn ______ in November our thoughts turn to our warm and sunny island off the coast of Florida frigid

179. ## Curriculum

Teacher intervention does NOT include a) statement of child's feelings b) seperation of all children involved c) statement of what that could or couldn't do d) simple, clear reason for restrain.. Is b) seperation of all children sound correct?

180. ## Chemistry

Why is a dilute solution of boric acid H3BO3 used as an eyewash? How does it work in cleansing the eye from chemicals?

181. ## math

y=-2x-1 how to set up to find what x is, this needs to graph as a linea equation.

182. ## physics

A 5 kg ball rolls off a 34 m high cliff, and lands 29 m from the base of the cliff. Express the displacement and the gravitational force in terms of vectors and calculate the work done by the gravitational force. Note that the gravitational force is < 0,

183. ## Lang, Arts

4. Which of the following sentences is a compound sentence? A.Charlie said it’s cold outside but hot in his bedroom. B.Jared enjoys eating eggs and bacon for breakfast. C.Sierra can’t decide between the blue and the black shoes. D.Thomas is meeting us

184. ## AlgebraB-2

I need help with figuring out how to do these problems to get the right answer. Appreciate any help. Thanks. Multiple choice: 1. What is the value of n so that the expression x² + 12x + n is a perfect square trinomial? 6 36 72 144 2. What are the

185. ## math

draw the following and name them find missing angles... a trinagle has sides 4in,6in and 9in

186. ## George Carver

If the length or the triangle is 35 and the base is 53 what is the length of the other side of the triangle.

187. ## Chemistry

Calculate the volume of oxygen starndad temperature and pressure which theoretically could be obtained from the 50cm3 of the solution of hydrogen peroxide containing 68g/dm3

188. ## stats

A random sample of n=16 scores is obtained from a population with a mean of µ= 80 and a treatment is administered to the sample. After treatment, the sample

which fraction is grater than 1/3 A. 1/2 B. 1/4 C. 1/5 D. 1/6

190. ## maths-surface area

there is a groove which is in a cylindrical form and is made in a cylindrical piece of wood of length 17.5cm. The groove is filled with graphite and the cylindrical graphite block is of same length as that of wooden piece. If the diameter of the graphite

191. ## Math

What type of graph does not show the number of times a response was given? (1 point) a.box-and-whisker plot b.line plot c.stem-and-leaf plot d.bar graph I choose c is that correct

192. ## maths

12 MEN AT A CAMP HAVE FOOD TO LAST 10 DAYS. IF 3 MEN JOIN THE CAMP.HOW LONG WILL THE FOOD LAST?

193. ## Chemistry

Find the pH: 1) A 0.001M solution of HCl 2) A 7.98 x 10^-2 M solution of HNO3 3) 1098L of a solution containing 8.543moles of HBr 4) 120mL of a solution containing 0.005 grams of hydrochloric acid. Please help me with these four. Out of 20 questions i only

194. ## psychology statistics for behavioral sciences

A multiple-choice test has 48 questions, each with four response choices. If a student is simply guessing at the answers, a. What is the probability of guessing correctly for any question? b. On average, how many questions would a student get correct for

which fraction is less than 2/5 A. 2/3 B. 3/5 C. 3/4

196. ## Math

Is the equation sinx + cosx = 1 an identity? Why?

197. ## Accounting 1

Red Bank Enterprises was involved in the following transactions during the fiscal year ending October 31: 8/2: Borrowed $75,000 from the Bank of Kingsville by signing a 120-day note. 8/20: Issued a$40,000 note to Harris Motors for the purchase of a

198. ## Chemistry

How do the following solutions show the properties of a buffer? 1) 50 ml 0.10 M NH3 + 50 ml 0.10 M NH4NO3 2) 10 ml solution #1 + 5 ml H2O + 1 ml 0.10 M HCl 3) 10 ml solution #1 + 6 ml 0.10 M HCl 4) 10 ml solution #1 + 5 ml H2O + 1 ml 0.10 M NaOH

199. ## PreAlgebra

Math estimate quotient 6 1/3 divided by 3 1/7

Benny is using base ten blocks to model 57 divided by 3. he divided the tens in to equal groups. he converted the remaining 10's in to 20 ones. then he divided 20 by 3, and put the ones into equal groups of 6, with 2 leftover. what did he forget to do?

201. ## maths-area of parallelogram

There is a man who plotted a land in shape of a trapezium with its parallel sides to be 15m and 5m & height=9m. The Panchayat decided to take a triangular plot of land from one side to construct a school. He reluctantly agrees to this. is this can be

202. ## English

Word box compact earmark scant strident Since the time we have to prepare for the final exams is exceedingly ____ we had better make the best of every hour This one is compact or scant? I think it's compact

203. ## algebra2

A farmer has 600 yards of fence. He will use some of the fence to enclose a rectangular area. He will use the rest divide the area into two congruent rectangles. What is the value of x that results in largest area? What is the largest area that the farmer

204. ## geometry

Lin says that a hexagon has six sides. Chris says that it has eight sides. Whose statement is correct?

205. ## Chemistry

7. A solution is prepared by dissolving 8.5 g NaHCO3 and 12.7 g Na2CO3 in 500.0 mL of water. Calculate the pH.

206. ## physics

Two masses of 8 kg and 12 kg are tied to each end f a string passing over a massless and frictionless pulley. find the resulting accelration of each mass.

207. ## physics

You're in an auto traveling at 25.0m/s toward a pole mounted warning siren. If the siren's frequency is 365 Hz, what frequency do you hear? Use 343m/s as the speed of sound.

208. ## Derivative

Find dy/dx for the following: 1) x^3 + 3x^2*y + y^3 = 4 I get -3(x+2y)/x^2 + y^2 it's wrong though. 2) x + y^2= xy^2 I get y^2 + 1/ 2y- 2xy this is also wrong. can you explain thanks

209. ## math

Chelsea has 3 quarters and 1 dime. James has 8 dimes. Peter has 2 quarters and 6 nickels. Denika has 10 nickels. Who has the most money?

210. ## physics

a 3 m long weightless beam is supported at each end by cables. a painter weighing 90 N stands 1 m from the left cable. Calculate the tension in each cable.

211. ## Chemistry

7. A solution is prepared by dissolving 8.5 g NaHCO3 and 12.7 g Na2CO3 in 500.0 mL of water. Calculate the pH.

212. ## AP Physics

Two particles, each of mass m and speed v, travel in opposite directions along parallel lines separated by a distance d. (a) Find an expression for the magnitude L of the angular momentum of the two-particle system around a point midway between the two

213. ## Derivatives

with respect to x f(cos x) if f'(x)= 1/x find (f(cos x))' i got tan x sec x this is wrong. can you explain thank you

214. ## English

Writeacher, I think I have one Flames Powerful red burning swooshing killing fire hot snow hail Freezing cracking slipping clear cold ice

262. ## Math Ms. Sue please

1. What type of graph does not show the number of times a response was given? (1 point) box-and-whisker plot line plot stem-and-leaf plot bar graph 2. Which of the following types of information is suited for display on a scatter plot? (1 point)

263. ## physical

An electric field with a magnitude of 3.50 kN/C is applied along the x axis. Calculate the electric flux through a rectangular plane 0.350 m wide and 0.7 m long assuming that (a) the plane is parallel to the yz plane; (b) the plane is parallel to the xy

264. ## algebra 1

write in scientific notation and standard form. (1.9x10 to the second power)times (4.7x10 to the 6th power) how do you do this?

265. ## CHEMISTRY

How do you get the concentration with buret readings? What would the concentration of HC2H3O2 (M) be? For example, Molarity of the NaOH solution: 0.2619 M Final buret reading: 31.10 ml Initial buret reading: 0 Volume of NaOH solution: 31.0 ml concentration

266. ## Physics

A certain car is capable only of accelerat ing at 3.0m/s 2 , braking (decelerating) at 5.0m/s 2 , and moving at constant velocity. The car is init ially located 100m from a road sign. The driver, starting from rest, begins to accelerat e towards the sign.

267. ## math

harriet and harry got jobs at the bumblo gum factory as bubblegum testers. for every bubble they blow they get 50 cents. harriet blows 100 bubbles and harry blows 150 bubbles. harry says, "wow! between the two of us, we've only made 12.50 today!" what was

268. ## algebra1

f(x)=-12xsquared+56x. where x is the time in seconds after it is shot how long was the pebble in the air

269. ## transport economics

how to analyse ITP

270. ## Biology

What was a event in Darwins life that lead him to the theory of evolution. When i googled it those were the only two that came up. And our teacher told us to not to do those

271. ## Maths

What is the highest power of 3 that divides 1000! (1000 factorial)

272. ## Math

What should you say when u meet and angle?

273. ## chemistry

The most common source of copper (\rm Cu) is the mineral chalcopyrite (\rm CuFeS_2). How many kilograms of chalcopyrite must be mined to obtain 210.g of pure \rm Cu?

274. ## English

Click on the box to choose the function of the italicized infinitive phrase. May I have permission to use the car tonight? I think its adjective.

275. ## Motivation and Emotion

How would the behaviourist perspective of psychology explain the motivation behind the long hours and irregular schedule resulting in sleep deprivation in dancers.

276. ## life orientation

8 ways in which the environmental problem impact within south africa

277. ## CTU

assuming the economy has gotten better andthat the funds now have a return of 7.72% compounded monthly. Diane salary has risen now she can contribute \$1000 a month. At the end of the next 15 yrs, how much is her account worth.

278. ## math

2/5 cut from 100ft rope how many feet is there

279. ## chemistry

if a total of 18.6 mol of NaHCO3, and 6.2 mol of C6H8O7 react, how many moles of CO2 and Na3C6H5O7 will be produced?

280. ## math

A polling company took 5 polls in the week before and election. It showed that a mayoral candidate would get 66%, 56%, 55%, 60%, and 63% of the votes. That candidate received 64% of the total votes during the actual election. Find the percent error in the

281. ## math

If r = 12.5 and s = |−13|, which of the following inequalities is not true??? 1.r≠s 2.r< s 3.r≥s 4.r≤s

282. ## Math

As many 8cm diameter discs as possible are cut from a sheet of rectangular cardboard measuring 170cm by 90cm. Find the area of the sheet that is left.

283. ## Math

A gasoline tank contains 500 liters of gasoline. By the end of each day, 70% of the gasoline remains. When will there be less than 100 liters in the tank?

284. ## Math

If the minute hand of a big clock is 1.12m long, find the rate at which its tip is moving in centimeters per minute.

285. ## chemistry

How many Liters of a 5.00 M Zn(NO3)2 would be needed to react with 200 g of (NH4)2S?