# Rob

Most popular questions and responses by Rob-
## general chem

Determine the oxidation number for the indicated element in each of the following compounds: (a) Co in LiCoO2, (b) Al in NaAlH4, (c) C in CH3OH (methanol), (d) N in GaN, (e) Cl in HClO2, (f) Cr in BaCrO4.

*asked on October 9, 2011* -
## general chem

Using the activity series (Table 4.5), write balanced chemical equations for the following reactions. If no reaction occurs, simply write NR. (a) Nickel metal is added to a solution of copper (II) nitrate; (b) a solution of zinc nitrate is added to a

*asked on October 9, 2011* -
## Chemistry

Use the data given below to construct a Born - Haber cycle to determine the electron affinity of Br? DH°(kJ) K(s) → K(g) 89 K(g) → K⁺(g) + e⁻ 419 Br2(l) → 2 Br(g) 193 K(s) + 1/2 Br2(g) → KBr (s) -394 KBr(s) → K⁺(g) + Br⁻(g) 674 I know

*asked on December 8, 2012* -
## general chem

Calculate the molarity of a solution made by dissolving 12.5 grams of Na2CrO4 in enough water to form exactly 550 mL of solution. (b) How many moles of KBr are present in 150 mL of a 0.275 M solution? (c) How many milliters of 6.1 M HCl solution are needed

*asked on October 9, 2011* -
## math

Lois wants to send a box of oranges to a friend by mail. The box of oranges cannot exceed a mass of 10 kg. If each orange has a mass of 200g, what is the maximum number she can send?

*asked on April 18, 2012* -
## Math

It takes an older pump 4 times as long to drain a certain pool as it does a newer pump. Working together, it takes the two pumps 4 hours to drain the pool. How long will it take the older pump to drain the pool working alone?

*asked on January 31, 2016* -
## chemistry

The equation for burning C2H2 is 2C2H2(g) + 5O2(g) ⎯→ 4CO2(g) + 2H2O(g) a. If 15.9 L C2H2 react at STP, how many moles of CO2 are produced? (Hint: At STP, 1 mol = 22.41 L for any gas.) b. How many milliliters of CO2 (density = 1.977 g/L) can be made

*asked on June 2, 2010* -
## Microeconomics

Pharmaceutical drugs have an inelastic demand, and computers have an elastic demand. Suppose that technological advance doubles the supply of both products (that is, the quantity supplied at each price is twice what it was).

*asked on November 22, 2010* -
## physics

A 16-kg sled is being pulled along the horizontal snow-covered ground by a horizontal force of 35 N. Starting from rest, the sled attains a speed of 2.1 m/s in 9.5 m. Find the coefficient of kinetic friction between the runners of the sled and the snow.

*asked on October 4, 2012* -
## math

Ms. Handler walks to work at an average speed of 5 kilometers per hour. If she increases her speed to 6 kilometers per hour, she will save 10 minutes. Find the distance she walks.

*asked on October 12, 2015* -
## Physics

A marble and a cube are placed at the top of a ramp. Starting from rest at the same height, the marble rolls without slipping and the cube slides (no kinetic friction) down the ramp. Determine the ratio of the center-of-mass speed of the cube to the

*asked on November 8, 2015* -
## Math (Confused)

A certain economy's consumption function is given by the equation C(x)=0.75x+5 where C(x) is the personal consumption expenditure in billions of dollars and x is the disposable personal income in billions of dollars. Find C(0), C(50), and C(100). a.

*asked on October 17, 2016* -
## Programming

Here is the source code for the Kitty class: public class Kitty { String name; int age; public Kitty(){ } public void setName(String n){ name = n; } public String getName(){ return name; } public void setAge(int a){ age = a; } public int getAge(){ return

*asked on October 28, 2009* -
## math ; Geomentry

A Ferris wheel is drawn on a coordinate plane so that the first car is located at the point (40,0). What are the coordinates of the first car after a rotation of 270 degrees counterclockwise about the origin?

*asked on October 9, 2017* -
## math quick question

I got a problem that states which graph represents the sequence of 1,2.5,4,5.5,7.. Should the graph start at 1,1 or 0,1?

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

Two wires run from the top of a pole 2.6m tall that supports a volleyball net. The two wires are anchored to the ground 2.0m apart, and each is 2.0m from the pole. The tension in each wire is 100N. here are the dimensions. I do not understand how to setup

*asked on March 17, 2013* -
## chemistry

How many grams of NaOH are present in 5.0 mL of a 1.0% (m/v) NaOH solution?

*asked on April 25, 2008* -
## Physics

A mass of 2.2kg is placed on a stiff vertical spring which has a spring constant of 950n/m. The object is then pressed against the spring until it has been compressed a distance of 77cm. The mass is then released and is allowed to be thrown up into the

*asked on February 25, 2012* -
## Statistics

Use the given data to find the minimum sample size required to estimate a population proportion or percentage. Margin of error: 0.06; confidence level 90% ^p and ^q unknown n= (round up to the nearest integer)

*asked on April 30, 2013* -
## Physics

For a resonance tube apparatus (open ended on one side) with a total tube length of 1.00 meter, on a day when the speed of sound is 340 m/s, how many resonance positions will be observed as the piston position is varied for a frequency of 500 Hz? and 1000

*asked on July 1, 2007* -
## Geometry

Ann went on a 10 hour bicycle trip. The graph models the relationship between the time and the total distance traveled by Ann. The table shows selected points on the graph. T=0,1,4,7,10 d(t)=0,3,5,5,10 draw a graph of anns speed in mph in terms of the time

*asked on May 27, 2014* -
## math

whats th eanswer to the math page. why do elephants have ivory tusks? and the answer to what can you use to tie up a spaceship?

*asked on June 6, 2012* -
## Physics

Explain how redioactive decay has always warmed the Earth from the inside and how nuclear fusion has always warmed the Earth from the outside.

*asked on April 25, 2008* -
## physics

A ball is dropped from a cliff and 2 seconds later, a second ball is thrown vertically downward. What must be the initial velocity of the second ball if it overtakes the first ball as it passes 400m ?

*asked on July 26, 2017* -
## Trigonometry

A little boy is flying a kite. The string of the kite makes an angle of 30 dgrees with the ground. If the height of the kite is h equals 15 m, find the length (in meters)of the string that the boy has used.

*asked on January 24, 2010* -
## Microeconomics (full version)

Pharmaceutical drugs have an inelastic demand, and computers have an elastic demand. Suppose that technological advance doubles the supply of both products (that is, the quantity supplied at each price is twice what it was). a. What happens to the

*asked on November 22, 2010* -
## 8th grade

a rabbit can climb one or two steps at a time on a ten step staircase, but he never goes back down. In how many different ways can the rabbit climb a flight of ten steps

*asked on January 26, 2010* -
## Organic Chemistry

What is the order of reactivity from fastest to slowest in an SN2 reaction for the following substrates? a. t-butyl bromide b. isopropyl bromide c. neopentyl bromide d. ethyl bromide e. methyl bromide So far have methyl bromide> ethyl bromide> neopentyl

*asked on March 24, 2019* -
## Math

A world record was set in Eco-Marathon by a french team in 2003 called Microjoule with a performance of 10,705 miles per gallon. The microjoule runs on ethanol. If the cars are given 100 grams of ethanol (specific gravity = .789) and drive until the fuel

*asked on February 7, 2016* -
## Chemistry

Give the name or formula of a reagent other than sodium metal that will convert cyclopentanol to sodium cyclopentoxide.

*asked on April 1, 2019* -
## Algebra Readiness

A right triangle is shown below. a=6 b=8 c=? The triangle is dilated by a scale factor of 2.5 to create a new triangle. What is the perimeter of the new triangle? answs; 120,24,60 and 150 i keep getting different answers can someone help?

*asked on November 30, 2018* -
## Physics

Why should a tuning fork be set into oscillation by striking it with a soft rubber mallet rather than with a hard metal mallet? Striking it with a hard mallet excites higher order modes rather than mainly the fundamental. That is because a hard mallet

*asked on July 1, 2007* -
## physics

Two wires run from the top of a pole 2.6 tall that supports a volleyball net. The two wires are anchored to the ground 2.0 apart, and each is 2.0 from the pole. The tension in each wire is 100. I do not understand how to setup work. if could show I would

*asked on March 17, 2013* -
## math

in one elementary school class the following information on sports preferences was obtained: 7 liked tennis; 11 liked baseball; 9 liked soccer; 5 liked tennis and baseball; 3 liked baseball and soccer; 2 liked tennis and soccer; and 2 liked all three

*asked on June 13, 2012* -
## Physics

Which process would release energy from gold, fission or fusion? Which would release energy from carbon? From iron?

*asked on April 25, 2008* -
## Math Help TIMED!

write the polynomial in standard form then name the polynomial based on its degree and number of terms 10 g - 7 g^3 + 2g^2 - 5 a. -7g^3 + 2g^2 + 10g - 5 cubic polynomial b. -5 + 10g + 2g^2 - 7g^3 cubic binomial c. 7g^3 - 2g^2 + 10g - 5 quadratic binomial

*asked on June 5, 2017* -
## chemistry

what is the balanced equation for the reaction of potassium dichromate and potassium hydrogen phthalate?

*asked on January 10, 2013* -
## calculus

A particle moves along a straight line with equation of motion s = f(t), where s is measured in meters and t in seconds. Find the velocity and speed when t = 9. f(t) = t ^-1 - t

*asked on February 24, 2010* -
## social studies

who does John Hancock resemble, and how?

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

How do you find a step that has the largest rate constant in the forward reaction? When looking at a potential energy diagram

*asked on March 25, 2019* -
## Chemistry

Calculate the frequency of a photon of orange light whose wavelength is 6.2*10^5m. (meters)

*asked on October 31, 2011* -
## Math

Latoya has 3/4 of a bag of popcorn. If she eats half of the popcorn at a movie, ho much does she have left?

*asked on November 1, 2010* -
## math

Find the volume of the figure. the figure is in the website below. For calculations involving π, give both the exact value and an approximation to the nearest hundredth of a unit. Let d = 8 and h = 18. www.webassign.net/aufexc3/7-4-002-alt.gif

*asked on December 7, 2018* -
## Science

A car's engine is only 12% efficient at converting chemical energy in gasoline into mechanical energy. If it takes 1.8 x 104 N of force to keep the car moving at a constant speed of 21 m/s, how much chemical energy would be needed to move the car a

*asked on July 18, 2012* -
## Chemistry

For a π bond, p orbitals should be________ when they overlap. As a result, in the E2 mechanism, an _______ elimination is said to occur. I tried "p orbitals should be parallel when they overlap. As a result, in the E2 mechanism, an antiparallel

*asked on April 11, 2019* -
## Physics

A spring is mounted horizontally. A crate which has a mass of 8.5kg is pressed against the spring with a force of 350N. As a result the spring is compressed a distance of 82.0cm. The mass is then released and is allowed to slide along the horizontal,

*asked on February 25, 2012* -
## Chemistry

If you are using 5.25% (mass/mass) bleach solution and you determine that the density of the bleach solution is 1.08 g/mL, how many moles of sodium hypochlorite are present in a 4.00 mL sample?

*asked on January 31, 2012* -
## Chemistry

The major factor affecting why boron and hydrogen add across a double bond in an apparent anti-Markovnikov manner (i.e. H adds to the more substituted side) in hydroboration is

*asked on April 29, 2019* -
## Math Help

A server purchased at a cost of $108,000 in 2002 has a scrap value of $18,000 at the end of 5 years. Find the linear equation expressing the server's book value at the end of t years. a- V(t)=108,000 b- V(t)=108,000t-18,000t c- V(t)=18,000t+108,000 d-

*asked on October 17, 2016* -
## Microeconomics

Pharmaceutical drugs have an inelastic demand, and computers have an elastic demand. Suppose that technological advance doubles the supply of both products (that is, the quantity supplied at each price is twice what it was).

*asked on November 22, 2010* -
## algebra

the acme widget company has $13,000 available for making widgets. part of the money is spent on an advanced widget-bending machine costing $1,000. the manufacturing cost for each widget is $3. how many widgets can be made with the money available?

*asked on October 9, 2010* -
## Math

Put in order from least to greatest: 0.748 11/16 76%

*asked on January 22, 2014* -
## Business

Communist Prison Camp In such prisons the total regimen, consisting of physical privation, prolonged interrogation total isolation from former relationships and sources of information, detailed regimentation of all daily activities, and deliberate

*asked on October 15, 2010* -
## math

what is 1+2

*asked on August 22, 2019* -
## Physics

Tom Brady passes a football – at a velocity of 50 ft/s at an angle of 40 degrees to the horizontal – toward an intended receiver 30 yd straight downfield. The pass is released 5 ft above the ground. Assume that the receiver is stationary, is isolated

*asked on April 25, 2011* -
## Math Finance

Word problem asks to find rate of interest on a monthly deposit for a sinking fund that is needed to produce 130,000 in 20 years. I applied the model, (fv/pv)^1/t -1 I use n/t if compounding yearly, quaterly, etc. No matter what I've tried I can't produce

*asked on July 3, 2014* -
## Chemistry

Sketch the titration curve for the tirtation of (0.10M) HCl vs 25.0mL (0.50M) NaOH

*asked on April 7, 2013* -
## Math

For a period of time as an alligator grows, its mass is proportional to the cube of its length. When the alligator's length changes by 15.8%, its mass increases by 17.3kg. Find its mass at the end of this process.

*asked on August 19, 2008* -
## ph

A coin slides over a frictionless plane and across an xy coordinate system from the origin to a point with xy coordinates (3.0 m, 5.8 m) while a constant force acts on it. The force has magnitude 2.8 N and is directed at a counterclockwise angle of 100°

*asked on November 29, 2014* -
## Econ

In which of the following circumstances would a buyer be indifferent about buying a good? a. The amount of consumer surplus the buyer would experience as a result of buying the good is zero. b. The price of the good is equal to the buyer's willingness to

*asked on March 30, 2009* -
## physics

A lighthouse that rises 46.0 ft above the surface of the water sits on a rocky cliff that extends 19 ft out into the ocean from the base of the lighthouse. A sailor on the forward deck of a ship sights the top of the lighthouse at an angle of 25.0 degrees

*asked on September 9, 2012* -
## Science

A supersonic jet flying at 145 m/s is accelerated uniformly at the rate of 23.1 m/s squared for 20.0 s. a. What is its final velocity? b. The speed of sound in air is 331 m/s. How many times the speed of sound is the plane's final speed? I don't care what

*asked on October 5, 2006* -
## Physics

A 25kg crate is sitting at the bottom of an inclined plane. The inclined plane 12m long meets the horizontal at an angle of 15 degrees and has a coefficient of friction of 0.55. A force is applied to the crate so as to slide the crate up the incline at a

*asked on February 25, 2012* -
## math

Given ABCD with A = (1,1),B = (4, 2), C = (4, 5), and D = (1, 4),what are the coordinates for Point D' if the y-axis is the reflecting line?

*asked on August 16, 2013* -
## Physics

A student applies a force of magnitude 39.0 N at an angle of 22.6o with the horizontal to push a 4.00-kg textbook 1.00 m across a table from rest to a final speed of 1.75 m/s. Find the work done by friction on the textbook.

*asked on July 18, 2012* -
## Machanics

particles of mass 3m and 5 m hang one at each end of a light inextensible string which passes over a pulley.The system is released from rest with the hanging parts taunt and vertical.During the subsequent motion the resultant force exerted by the string on

*asked on March 4, 2011* -
## math

particles of mass 3m and 5 m hang one at each end of a light inextensible string which passes over a pulley.The system is released from rest with the hanging parts taunt and vertical.During the subsequent motion the resultant force exerted by the string on

*asked on March 4, 2011* -
## grammar

in the sentence "He felt hungry and thought about the lunch wrapped in his handkerchief." which are the linking verbs and which are the action verbs?

*asked on October 12, 2010* -
## physics

light from the sun travels 1.5x10km to reach the earth .how long does it journey take in minutes?

*asked on August 9, 2015* -
## Physics

A box which has a mass of 14kg is sliding along a horizontal surface with a velocity of 18m/s when it encounters a frictionless inclined plane which meets the horizontal at an angle of 28 degrees. The box slides up the incline until it comes to a halt. How

*asked on February 25, 2012* -
## general chem

Calculate the molarity of a solution made by dissolving 12.5 grams of Na2CrO4 in enough water to form exactly 550 mL of solution. (b) How many moles of KBr are present in 150 mL of a 0.275 M solution? (c) How many milliters of 6.1 M HCl solution are needed

*asked on October 9, 2011* -
## physics

i dont know what the answer is... i got itwrong my answer was 1.78. whats the correct answer? A 57kg trampoline artist jumps vertically upward from the top of a platform with a speed of 4.7m/s. How fast is he going as he lands on the trampoline 3.8m below?

*asked on May 16, 2018* -
## physics

a small child is sliding down a 25 degree slide at a uniform velocity of 1.0 m/s. If the child weighs 210 N, find the coefficient of friction between the slide and the child.

*asked on November 18, 2010* -
## Organic Chemistry

What is the product formed from a reaction of butanal and sodium hydroxide? cyclopentanone and sodium hydroxide? acetophenone and sodium hydroxide? Thanks. You want to look up information about the Aldol condensation.

*asked on March 6, 2007* -
## Statistics

Use the sample data and confidence level to construct the confidence interval estimate of the population proportion p. n=500, x=350, 90% confidence ?

*asked on April 30, 2013* -
## Physics

f a water bed is 1.81 m on each vertical side and 30 cm high. Find its weight. The acceleration of gravity is 9.8 m/s2 and the density of water is 1000 kg/m3. Answer in units of N

*asked on April 15, 2011* -
## Math

particles of mass 3m and 5 m hang one at each end of a light inextensible string which passes over a pulley.The system is released from rest with the hanging parts taunt and vertical.During the subsequent motion the resultant force exerted by the string on

*asked on March 3, 2011* -
## Science

How many kilograms of water can be evaporated at 100 degrees Celsius by the combustion of 470 litres of fuel oil whose heat of combustion is 37 MJ/Litre

*asked on June 26, 2017* -
## Statistics

A study of 420,048 cell phone users found that 135 of them developed cancer of the brain or nervous system. prior to this study of cell phone use the rate of such cancer was found to be 0.0333% for those not using cell phones. Complete parts (a) and (b) a.

*asked on April 30, 2013* -
## physics

Starting from rest, a 10.7 kg block slides 2.60 m down to the bottom of a frictionless ramp inclined 30.0° from the floor. The block then slides an additional 4.70 m along the floor before coming to a stop. (a) Determine the speed of the block at the

*asked on March 26, 2013* -
## physics

An acorn and tree leaf fall from the same height and time. Which reaches the ground first and why?

*asked on April 9, 2011* -
## corporate finance

Bank One is offering a 30yr mortgage with an EAR of 5 3/8%. You plan to borrow $150,000, what will your monthly payments be

*asked on October 20, 2010* -
## chem expirement!

You are required to design an experiment to test Hess's law using the combustion of ethanol. Write a brief design for this experiment. What I wrote as my answer: Hess’ Law: is the algebraic addition of chemical equations yields a net equation whose

*asked on May 17, 2007* -
## Calculus

Find the distance traveled by a particle with position (x, y) as t varies in the given time interval. x = cos^2 t, y = cos t, 0 ≤ t ≤ 9π and the length of the curve so far i got ∫0 to 9pi √((-2cos(t)sin(t))^2+(-sint)^2) I am having trouble

*asked on April 29, 2017* -
## Physics

Displacement vector A with arrow points due east and has a magnitude of 2.62 km. Displacement vector B with arrow points due north and has a magnitude of 2.26 km. Displacement vector C with arrow points due west and has a magnitude of 1.4 km. Displacement

*asked on September 12, 2014* -
## statistics

An obstetrician maintains that preterm babies (gestation less than 37 weeks) have a higher variability of birth weight than do full-term babies (gestation 37-41 weeks). According to the National Vital Statistics Report, Vol. 48, No. 3, the birth weights of

*asked on March 7, 2011* -
## physics 100

What minimum speed does a 160 puck need to make it to the top of a 5.4 -long, 24 frictionless ramp?

*asked on November 14, 2012* -
## Chemistry

When heated, N2O4 dissociates as follows: N2O4 =2NO2 A flask initially contians .560 M N2O4. at this temperature, Kc is 4.00. what is the equilibrium concentration of NO2?

*asked on November 4, 2010* -
## physics

A 0.69 kg mass is observed to accelerate at 8.16 m/s2 in a direction 30.5° north of east. There is a force directed north acting on the object and a force directed east acting on the object. What is the magnitude of the force acting east on the object?

*asked on November 3, 2010* -
## fischer esterification

which alcohol and carboxylic acid would produce benzyl isobutyrate by Fischer esterification? and which alcohol and carboxylic acid would produce isobutyl benzoate by fischer esterification? Since this is not my area of expertise, I searched Google under

*asked on March 4, 2007* -
## PHYSICS

2.- A man of 73 kg has a volume of 75 l, of which 5 l correspond to the lungs. (a) Calculate the volume of the lungs when going in apnea underwater to a depth of 10 m, assuming that the density of sea water is 103 kg/m3 . (b) At that depth, will the total

*asked on December 11, 2014* -
## Statistics

Assume that a random sample is used to estimate a population proportion p. Find the margin of error E that corresponds to the given statistics and confidence level. 95% confidence the sample size is 2096 of which 25%are successes The margin of E= (round to

*asked on April 30, 2013* -
## physics

A car is traveling at 25m/s when an accident occurs. The car decelerates 300m/s^2 but the passenger does not slow down because he is not wearing a seatbelt. a) Supposing the distance between the passenger and the dashboard is initially 0.50m, what will be

*asked on February 10, 2013* -
## math please

Which Represent the first two terms of the sequence a1=2 and an=-2(an-1)^2 2, -8 -8,-128 16,1024 -2,16

*asked on March 10, 2012* -
## Chemistry

If you are using 5.25% (mass/mass) bleach solution and you determine that the density of the bleach solution is 1.08 g/mL, how many moles of sodium hypochlorite are present in a 4.00 mL sample?

*asked on January 31, 2012* -
## Math

a plane flies due north at 300 mi/h for 3 h then due west at 250 mi/h. If x represents the number of hours the plane is flying due west, determine for what values of x the plane will be more than 3700 mi from it's original point.

*asked on March 8, 2011* -
## Algebra

A gardener has 60 feet of fencing with which to enclose a garden adjacent to a long existing wall. The gardener will use the wall for one side and the available fencing for the remaining three sides. (a) If the sides perpendicular to the wall have length x

*asked on November 21, 2010* -
## Physics

If a pair of carbon atoms were fused, and the product were to emit a beta particle, what element would be produced?

*asked on April 25, 2008* -
## Physics

Mixing copper and zinc atoms produces the alloy brass. What would be produced with the fusion of copper and zinc nuclei?

*asked on April 25, 2008* -
## Calc Jacobian

Thanks "I know that the xy region is the line x=y y=0 and y=1- x/2)" It is helpful to rewrite the region in the x-y plane by specifying the three lines and the endpoints, i.e. the points where they intersect. If you insert these points in the formula for U

*asked on December 4, 2006*