# Christina

Popular questions and responses by Christina-
## Chemistry

What is the ionic and net ionic equation for Na2CO3 + 2 HNO3 -> 2 NaNO3 + H2O + CO2 (g) This is what i have so far... Na2(aq)+CO3+H+NO3 -> Na+ NO3+ H2O(l)+CO2(g)... i don't know what to do!!!

*asked on November 3, 2009* -
## Calculus

Suppose f(pi/3) = 3 and f '(pi/3) = −7, and let g(x) = f(x) sin x and h(x) = (cos x)/f(x). Find the following. a. g'(pi/3) b. h'(pi/3)

*asked on November 7, 2011* -
## Chemistry

A 2.52g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess O to yield 4.36g of CO2 and 0.892g of H20. Another sample of the same compound of mass 4.14g, yielded g of SO3. A third sample, of mass, 5.66g,

*asked on September 6, 2010* -
## Algebra

The back of Tom's property is a creek. Tom would like to enclose a rectangular area, using the creek as one side and fencing for the other three sides, to create a corral. If there is 100 feet of fencing available, what is the maximum possible area of the

*asked on October 5, 2015* -
## Physics -Interference & Diffraction

Given Information: Light of wavelength 631 nm passes through a diffraction grating having 485 lines/mm. Part A: What is the total number of bright spots (indicating complete constructive interference) that will occur on a large distant screen? *Answer: 7

*asked on April 11, 2008* -
## Physics

A boat is being towed through a canal by means of ropes which make a 45 degree angle to each other. If a force of 75N is applied to the rope, what is the resultant force pulling the boat forward?

*asked on November 3, 2013* -
## Science

In the early 1900s, Alfred Wegener noticed that some of the Earth's continents looked like they might fit together like a jigsaw puzzle. He also observed that the continents that looked like they fit together had similar plants, animals, and rock

*asked on August 15, 2014* -
## Calculus

The number N of US cellular phone subscribers (in millions) is shown in the table. (Midyear estimates are given.) t 1996 1998 2000 2002 2004 2006 N 44 69 109 141 182 233 (a) Find the average rate of cell phone growth between the following years. In each

*asked on October 29, 2011* -
## Calculus

The area A of the region S that lies under the graph of the continuous function is the limit of the sum of the areas of approximating rectangles. A = lim n → ∞ [f(x1)Δx + f(x2)Δx + . . . + f(xn)Δx] Use this definition to find an expression for the

*asked on November 24, 2013* -
## calculus

Find the limit. Use l'Hospital's Rule if appropriate. If there is a more elementary method, consider using it. lim x→∞ {(5x − 4)/(5x + 3)}^5x + 1

*asked on March 17, 2017* -
## math

At Strawberry State College, the ratio of females to males is 2:1. If there are 2100 students, how many are female and how many are male?

*asked on November 16, 2012* -
## physics

Find the linear speed of the bottom of a test tube in a centrifuge if the centripetal acceleration there is 5.5×104 times the acceleration of gravity. The distance from the axis of rotation to the bottom of the test tube is 8.0 .

*asked on March 25, 2011* -
## science (chem)

For the preparation and standardization of NaOH with KHP im supposed to boil water for 1hr and 30 min to remove CO2....the problem is that if I don't boil it for that long and (30 min) b/c of not enough time but I put the water I boiled for 1/2 hr

*asked on June 22, 2007* -
## medical billing

for medicaid cases there is no assignment of benefits unless the patient has other insurance in addition to medical. true or false 2. a two or three form that incorporates a bill, insurance form,and routing document used both computer and paper based

*asked on April 23, 2011* -
## Biology

Explain why a heavy rainfall on a fruit orchard in the spring might result in a poor fruit yeild in the fall.

*asked on May 5, 2010* -
## Physical Science

If you were to expend 10 Joules of work to push a 1-coulomb charge against an electric field, what would be its voltage with respect to its voltage in its starting position? When released, what will be its kinetic energy if it flies past its starting

*asked on September 9, 2009* -
## calculus

Find the limit. Use l'Hospital's Rule if appropriate. If there is a more elementary method, consider using it. lim x→0 (e^x − e^−x − 2x)/(x − sin(x))

*asked on March 17, 2017* -
## Chemistry

Rank the following in order of increasing bond polarity: H-F, H-Br, F-F, Na-Cl. Is it this....? F-F, H-Br, H-F, Na-Cl

*asked on November 22, 2015* -
## Physics

The Achilles tendon, which connects the calf muscles to the heel, is the thickest and strongest tendon in the body. In extreme activities, such as sprinting, it can be subjected to forces as high as 13.0 times a person's weight. According to one set of

*asked on November 13, 2007* -
## Business English

Write a paragraph describing your attitudes toward writing. Use the following steps. Prewrite: Jot down a few of the words that come to mind when you think of writing. Think of any significant experiences you have had that have shaped your attitude toward

*asked on January 23, 2019* -
## science(chem) Dr.Bob (activity coeficent)

When a 0.1M solution of weak acid HA was titrated with a 0.1M NaOH. The pH measured when Volbase=1/2Voleq point was 4.62. Using the activity coeficents, calculate pKa. fA-=0.854 and fHA=1.00 For this I'm confused once again. I know that using the activity

*asked on July 24, 2007* -
## Science

In a new system of unit called star unit 1*kg=10kg,1m*=1km,1s*=1min. Convert 1J of energy in new system of unit.

*asked on June 17, 2018* -
## chemistry

A STUDENT STUDYING THE FE+3- HSCN equilibrium put into a test tube 10.00ml of 2.00 x 10-3 M Fe(NO3)3 with 10.0 mL of 2.00 x 10-3 M HSCN.THE H+ in the resulting solution was manteined at 0.500.By spectrophotometric analysis of the equilibrium solution, the

*asked on September 29, 2012* -
## Chemistry

Calculate the boiling point elevation of a solution made from 15.0 g of a nonelectrolyte solute and 250.0 g of water. the molar mass of the solute is 50.0 g and Kb = 0.51 degrees C/m

*asked on June 7, 2010* -
## Physics-help please!

You decide to use your body as a Carnot heat engine. The operating gas is in a tube with one end in your mouth (where the temperature is 37.0 C) and the other end at the surface of your skin, at 30.0 C. What is the maximum efficiency of such a heat engine?

*asked on December 15, 2007* -
## English

What is the difference between the denotative and connotative meaning of a word?

*asked on February 2, 2015* -
## Chemistry

Write the class/family of the following compounds and the functional group in each compound. a. 3-methylcyclohexene b. Cis-3-octene c. 4-methyl-2-heptanone d. 3-bromobenzaldehyde e. 3-bromo-5-chlorotoluene f. 3-chlorophenol g. 6-methyl-2-heptyne Please

*asked on April 22, 2014* -
## AP Chemistry

CH3NH2(aq)+H2O(l)=>CH3NH3+(aq)+OH-(aq) Kb=4.4 x 10^-4 Methylamine, CH3NH2, is a weak base that reacts with water according to the equation above. A student obtains a 50.0 mL sample of a methylamine solution and determines the pH of the solution to be

*asked on May 2, 2013* -
## Chemistry

A sealed flask contains 1 mole of hydrogen and 3 moles of helium gas at 20DC. If the total pressure is 40kPa, what is the partial pressure of the Hydrogen gas? AND :) The data below was obtained by a student in order to determine the percent of water in a

*asked on March 31, 2013* -
## chemistry

200. g of a nonelectrolyte is dissolved in 1.00 kg of water. the boiling point of the solution is then measured to be 101.5 degrees C. What is the molar mass of the compound? The Kb for water is 0.51 degrees Celsius/m

*asked on June 7, 2010* -
## social studies

The salesperson in medication ads dresses to look like a doctor because of what? 1. she has tested the product directly 2. the product was developed by physicians 3. FCC regulations demand this 4. the salesperson’s credibility is enhanced

*asked on December 20, 2009* -
## Physics

A small block on a frictionless horizontal surface has a mass of 2.50×10−2 Kg. It is attached to a massless cord passing through a hole in the surface. The block is originally revolving at a distance of 0.300 m from the hole with an angular speed of

*asked on November 7, 2007* -
## Chemistry

You have a solution of 0.500 M NaCl. If you add an equal amount of water to this solution, doubling the volume, what is the concentration of this solution?

*asked on October 15, 2017* -
## Algebra

Find the linear function with the following properties: f(0)=1 and the slope of f equals -3/2 THANK YOU

*asked on October 10, 2015* -
## math final review (help)

from a 12cm by 12cm piece of cardboard, square corners are cut out so that the sides can be folded up to make a box. Express the volume of the box as a function of the length, x, in centimeters.

*asked on December 16, 2012* -
## math

Jacob opens a savings account on January 1 with a deposit of $350. He has "direct deposit," in which $25 is deposited every other week. The bank also charges a $3 monthly processing fee. How much money will he have at the end of the year?

*asked on October 31, 2012* -
## PHYSICS!!!

A net force of 30 N is applied to a 10 kg object, which starts at rest. What is the magnitude of its momentum after 3.0 seconds? Can someone please explain this as you go through the steps? I already know the equation is p=mv and I know that mass is 10kg

*asked on June 2, 2012* -
## geometry

when two lines intersect, they form two pairs of "opposite" angles called _________ angles?

*asked on August 10, 2011* -
## physics

An automobile tire is rated to last for 45,000 miles. Estimate the number of revolutions the tire will make in its lifetime.

*asked on January 13, 2011* -
## chemistry

Calcium carbonate reacts with hydrochloric acid according to the following reaction: CaCO3 (s) + 2 HCl (aq) --> CaCl2 (aq) + H2O (l) + CO2 (g) How many grams of calcium carbonate would be required to neutralize 50.0 cm3 of 8.00 M HCl?

*asked on November 7, 2010* -
## maths

how do you write 2.089 in expanded form

*asked on December 13, 2007* -
## science( chem)

When 100.0ml of a weak acid was titrated with 0.09381M NaOH, 27.63ml were required to reach the equivalence point. The pH at the equivalence point was 10.99. What was the pH when only 19.47ml of NaOH had been added ? I'll just post my work and I need

*asked on July 22, 2007* -
## calculus

Find dy/dx by implicit differentiation. arctan(2x^2y)=x+4xy^2

*asked on March 17, 2017* -
## Statistics

A random sample of 100 cable TV movies contained an average of 3.38 acts of physical violence per program. At the 99% level what is your estimate of the population value? mean = 3.38 s = 0.30 N = 100

*asked on June 14, 2015* -
## Geography

Which of the following most accurately describes the difference between climate and weather? (1 point) Climate refers to long-terms conditions; weather refers to daily conditions. Climate refers to severe weather events; weather refers to precipitation.

*asked on August 25, 2014* -
## science

You measure the dimensions of a rectangular block of aluminum to determine its volume. It has the following dimensions. length = 10.27 cm; width = 4.92 cm; height = 1.53 cm Assuming that each of these measurements is accurate to the nearest 0.01 cm, find

*asked on February 3, 2014* -
## stats.

The GMAT test is required for admission to most graduate programs in business. In a recent year, the GMAT test scores were normally distributed with a mean of 550 and standard deviation of 100. A. Find the first quartile for the distribution of GMAT

*asked on March 18, 2013* -
## Stats.

The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of a group of 48 vehicles is selected find the probability that the mean of the group’s age is between

*asked on March 18, 2013* -
## Math

Use the distance formula to determine whether the points lie on the same line. (0,4),(7,-6),(-5,11). I know the distance formula, but I don't see how that will help me find out if they lie on the same line.

*asked on September 16, 2011* -
## Chemistry

Calculate the amount of heat (in calories) required to raise the temperature of 200g of water from 20C to 50C. The specific heat of water is 1.00 cal/g. I have done other spacific heat problems but on this one i don't know how to start...

*asked on November 10, 2009* -
## Physics -I'm stumped

Europa, a satellite of Jupiter, appears to have an ocean beneath its icy surface. Proposals have been made to send a robotic submarine to Europa to see if there might be life there. There is no atmosphere on Europa, and we shall assume that the surface ice

*asked on November 30, 2007* -
## Chemistry

calculate the pH of 0.025 mol dm^3 trioxonitrate (v) solution

*asked on June 16, 2020* -
## Chemistry

The percent composition by mass of an unknown compound with a molecular mass of 60.052 amu is 40.002% C, 6.7135% H, and 53.284% O. Determine the compound's empirical and molecular formulas.

*asked on October 10, 2017* -
## SS

How is this so far? and what else should i add, i need two pages and i have only one done, due today. help? I Josephine A. Walker was a slave for Harry Richardson. Every morning I had to serve him, I had to be up by 4am and was unable to go to bed till

*asked on January 29, 2015* -
## algebra

You deposit $3000 in an account earning 7% interest compounded continuously. The amount of money in the account after years is given by A(t)=3000 e^(0.07 t) . How much will you have in the account in 5 years? $ Round your answer to 2 decimal places. How

*asked on November 22, 2014* -
## math

Find, correct to the nearest degree, the three angles of the triangle with the given vertices.? A(2, 0),B(4, 5), C(-3,2) ANGLE- CAB ANGLE- ABC ANGLE- BCA In degrees. I got the vectors AB BC AC and I know the equation b.c= |b| |c| cos t

*asked on September 13, 2013* -
## Math

A standard deck of cards has four different suits:hearts ,diamonds ,spades, and clubs.Each suit has 13 cards, making a total of 52.Two cards are drawn without replacement. What is the probability of drawing first a heart, and then a spade?

*asked on May 29, 2013* -
## chemistry

Does molecular weight of water (H2O) = atomic weight of 2H + O = 2(1.008) + 15.999 = 18.015g ~ 18.02g (4. sig. fig.) is it correct?

*asked on December 3, 2012* -
## algebra

Solve by using the elimination method. 7x-8y=-20 8x+7y=74

*asked on August 13, 2012* -
## Physics :)

John and Joan walk in opposite directions around a circular path, starting from the same point. The path has a radius of 50.0 meters. John walks at 1.00 m/s, Joan at 1.25 m/s. How long will it take for them to meet? Can someone please explain this to me?!

*asked on June 8, 2012* -
## geometry

jo was comparing two cylinders that both had a radius of 5cm. the first had a height of 10cm, and the other a height of 20cm. How many times greater was the volume of the larger cylinder?

*asked on August 12, 2011* -
## geometry

a spherical water storage tank has a radius of 10ft. A cubic foot of water is about 7.5 gallons. How many gallons of water will the tank hold?

*asked on August 10, 2011* -
## chemistry

Salicyclic acid reacts with methanol to produce methylsalicyclate or winter green and water according to the following reaction: C7H6O3 (s) + CH3OH (l) --> C8H8O3 (s) + H2O (l) What mass methylsalicyclate can be produced from 15.00 grams of salcyclic acid?

*asked on November 8, 2010* -
## World History

How did civilized culture survive the rise and fall of regional states?

*asked on September 26, 2010* -
## chemistry

The mineral CaF2 has a solubility of 2.1 x 10^-4 M. What is the Ksp of CaF2? a. 1.85x10^-11 b. 9.3x10^-12 c. 3.7x10^-11 d. 8.8x10^-3

*asked on January 4, 2010* -
## english/ world geo.

Their are many lingering effects of communsim. I think the most important effects of communsim is the economic and political problems in Eastern Europe. please proofread ( might be factual or spelling punction etc.) there are 6 mistakes in this sentence.

*asked on December 14, 2009* -
## physics

You push a 45 kg wooden box across a wooden floor at a constant speed of 1.0 m/s. The coefficient of kinetic friction is 0.15. Now you double the force on the box. How long would it take for the velocity of the crate to double to 2.0 m/s?

*asked on November 21, 2009* -
## Chemistry

an exothermic reaction involves a. breaking weak bonds to form weak bonds. b. breaking weaker bonds to form stronger bonds c. breaking srtong bonds to form strong bonds. d. breaking stronger bonds to form weaker bonds. I think that it is a.

*asked on November 15, 2009* -
## social studies

A study of the causes of the American Revolution of 1776, the French Revolution of 1789, and the Russian Revolution of 1917 best supports the generalization that revolution is most likely to occur when

*asked on August 16, 2009* -
## english

i was just wondering does this song lyric have a metaphor? The stars will cry The blackest tears tonight And this is the moment that I live for I can smell the ocean air And here I am Pouring my heart onto these rooftops Just a ghost to the world That's

*asked on March 31, 2009* -
## science( chem)

Find the pH of a solution prepared by disolving 1.00g of glycine amide hydrochloride (BH+) (mwt=110.54g/mol) plus 1.00g of glycine amide (B)(mwt=74.08) in 0.10L PKa=8.04 I got pH= 8.21 Is that correct? This question actually has 4 extra parts but I wanted

*asked on July 21, 2007* -
## science(chem)

What is Zimmerman Reagent made of? (I know it is acidic b/c I was told after it burned a hole in my jeans) acid? You must mean Zimmermann-Reinhardt reagent (79 g MnSO4, 100 mL of concentrated H2SO4, and 200 mL of concentrated H3PO4, diluted to 1 L)

*asked on July 16, 2007* -
## science (chem)

Does EDTA react with light? I forgot to cover a dilute bottle of EDTA (about 0.01M) and was wondering if that would have any affect on the solution I don't think so. I have used EDTA many times and never covered it or used a tinted container. okay =) i

*asked on July 2, 2007* -
## poetry

i need to write a question poem with 10 lines and that asks a lot of questions i have no ideas please help! Pick a theme, then the questions, then put them in verse. Example: Theme Love questions.. What is how it began where will it lead how will it end

*asked on May 14, 2007* -
## Math URGENT!!

The speed of a runner increased steadily during the first three seconds of a race. Her speed at half-second intervals is given in the table. Find a lower estimate for the distance that she traveled during these three seconds. t(s) 0 0.5 1.0 1.5 2.0 2.5 3.0

*asked on April 14, 2007* -
## chemistry

For the endothermic physical change of water (liquid) into water vapor (gas), describe the entropy change, the enthalpy change, and use Gibb’s Free Energy to explain when this reaction will be spontaneous and when it will not.

*asked on April 26, 2020* -
## math

Express 37 1/2% as a fraction in its lowest terms.

*asked on October 21, 2018* -
## Calculus

Calculate μ and σ, where σ is the standard deviation, defined by the following. σ^2 = integral between (−∞,∞) (x-μ)^2 p(x) dx The smaller the value of σ the more tightly clustered are the values of the random variable X about the mean μ. p(x)

*asked on November 22, 2015* -
## Math 71x

One cell phone plan allows 200 text messages per month for $20 after which text messages cost $0.04 each. Another cell plan allows 400 text essages per month for $30 each. What would be the minimum text messages that would justify the more expensive plan

*asked on October 1, 2015* -
## geography

What are examples of human adaptation to the environment?

*asked on January 22, 2015* -
## Geography

Which of the following are impacts that the temperate climate has had on Georgia’s development? (1 point) encouraging crops with longer growing seasons drawing immigrants from other locations encouraging tourism all of the above 3. What impacts have

*asked on August 25, 2014* -
## Stats

Find the P-value for a left tailed hypothesis test with a test statistic of z= -1.77. Decide wether to reject the null if the level of significance is alpha= 0.05. Please help I've tried everything and I can't figure out how to get the right answer..

*asked on April 17, 2014* -
## Physics

Suppose we take a 1 m long uniform bar and support it at the 27 cm mark. Hanging a 0.31 kg mass on the short end of the beam results in the system being in balance. Find the mass of the beam.

*asked on March 28, 2014* -
## Physics

If an incline has a difference in height from one end to the other of 17.8 cm and has a length along the incline of 1.19 m, what is the angle that the incline makes with the horizontal reference surface?

*asked on February 15, 2014* -
## Science

The sensitivity of a measuring instrument is the value of the smallest quantity that can be read or estimated with it. What is the smallest part of a centimeter that can be read with the following? (a) a meterstick with markings at each millimeter I tried

*asked on February 3, 2014* -
## Physics

A test rocket is launched by accelerating it along a 200.0-m incline at 1.25m/s2 starting from rest at point A (the figure (Figure 1) .) The incline rises at 35.0 ∘ above the horizontal, and at the instant the rocket leaves it, its engines turn off and

*asked on February 1, 2014* -
## Physics

An explorer in the dense jungles of equatorial Africa leaves his hut. He takes 41 steps at an angle 45∘ north of east, then 81 steps at an angle 60∘ north of west, then 49 steps due south. Assume his steps all have equal length. Save him from becoming

*asked on January 19, 2014* -
## chemistry

write the balanced equation for the reactions of aquesous pb(CIO3)2 with aqueous Nal. include phases. 2.If a solution containing 86.044 g of mercury(II) chlorate is allowed to react completely cointaing 15.4888 g of sodium sulfide, how many grams of solid

*asked on September 24, 2013* -
## math

in order to be able to ride a roller coaster you must be 48 inches tall .which inequality represents this situation?

*asked on January 27, 2013* -
## ALGEBRA 2 urgent!!

if you have 200 feet of fencing to enclose four adjacent rectangular enclosures. Determine what demensions should be used so that the enclosed area will be maximized.

*asked on December 10, 2012* -
## Physics

Here's the question: A 55 kg swimmer is standing on a stationary 235 kg floating raft. The swimmer then runs off the raft horizontally with a velocity of +4.3 m/s relative to the shore. Find the recoil velocity that the raft would have if there were no

*asked on December 10, 2012* -
## math

If you are flying to a city 800 miles away, what will be the difference in flight times between flying into a 40-mph headwind and flying with a 40-mph tailwind if the plane's maximum speed with no wind is 160 mph?

*asked on November 1, 2012* -
## math

If you are flying to a city 800 miles away, what will be the difference in flight times between flying into a 40-mph headwind and flying with a 40-mph tailwind if the plane's maximum speed with no wind is 160 mph?

*asked on October 31, 2012* -
## math

The factors of a number include 9, 12, and 20. What is the smallest number this could be? List all the factors of this number

*asked on October 26, 2012* -
## math

The GCF of two numbers is 15. Their LCM is 450. What are the two numbers? (Enter your answers as a comma-separated list.)

*asked on October 26, 2012* -
## math

In order to make the most accurate calendar, the following system was devised. Leap years occur every 4 years except for years ending in 00, but years divisible by 400 are leap years. In this case, the year is a leap year if it is divisible by 400. Which

*asked on October 10, 2012* -
## algebra

Solve by the elimination method. 2x-7y=-36 7x+2y=33

*asked on August 12, 2012* -
## algebra

Calculate. 7[6+(8)^3]

*asked on July 25, 2012* -
## physics

Forces of 86 N east, 23 N north, 46 N south, 55 N west are simultaneously applied to a box of mass 13.8 kg. Find the magnitude of the box's acceleration?

*asked on June 18, 2012* -
## Physics

A stuntman sitting on a tree limb wishes to drop vertically onto a horse galloping under the tree. The constant speed of the horse is 10.0 m/s, and the man is initially 2.75 m above the level of the saddle. (a) What must be the horizontal distance between

*asked on February 7, 2012*