# Posts by Alice

Total # Posts: 727

Math
A set of homogeneous simultaneous equations is given by x + ky = 0 kx + 3y = 0 Calculate the two values of k that lead to non-trivial solutions to these equations and express y in terms of x for the two values. I thought that for the solutions to be no trivial the determinant ...

Chemistry
I am attempting to answer a question which asks to explain the sequence of pKaH values for a series of substituted guanidines (NH2)2CNR where R varies. The order is R = H , Ph , CH3CO , MeO , CN , NO2 pKaH = 14.5 , 10.8 , 8.3 , 7.5 , -0.4 , -0.9 I'm not quite sure how to ...

Maths
How can it be possible for a set of inhomogeneous simultaneous equations to have no unique solution?

Chemistry
Why do amides require much harsher conditions for hydrolysis than esters? I'm guessing amides are more stable for some reason, but I'm not completely sure. Is it conjugation?

Chemistry
Why does CdCO3 have a significantly lower decomposition temperature than CaCO3, despite the similarity in the ionic radii of Ca2+ and Cd2+? I think they both decompose to give the metal oxide and carbon dioxide. Could the polarising ability of Ca compared with Cd have ...

math
c 16

math
louis drew all of the possible diagonals from one vertex of a regular hexagon. Which of these statements is true? A) Each diagonal from this vertex is one of two different lengths B) None of the diagonals forms a line of symmetry of the hexagon. C) The diagonals form four ...

History- Opinion
Yes! Totally. It's sounds very good. Who said that? I've it before.

math
Are diagonals longer shorter or the same size as a regular pentagon's sides?

circuits
a parallel RLC bandpass circuit with C=10nF and Q=10 has a center frequency of 500 krad/s. Find R,L and the two cutoff frequencies. Can you design this circuit using a cascade connection of two first-order filters separated by a follower?

circuits
For the transfer function Tv(s)=[10(s+5)(s+20)]/[(s+1)(s+100)] is this a low-pass, high-pass, bandpass or bandstop function? estimate the corner frequency(ies) estimate the passband gain what is the output if v1(t)=10cos(1000t+45deg) V??

Chemistry
Which is the stronger base, NH3 or H2N-CH2COOH?

Chemistry
Why is the carbonyl group in tert-butoxycarbonyl group (tBOC) less susceptible to attack from nucleophiles than the carbonyl group in esters such as ethyl acetate? Is this something to do with conjugation?

maths
what is th area of 10,10,18,4,4,8,8,2 ?

Chemistry
Is this the correct equation for the formation of [Co(NH3)5(ONO)]^2+ from [Co(NH3)5Cl]^2+ ... [Co(NH3)5Cl]^2+ + NO2 --> [Co(NH3)5(ONO)]^2+ + Cl- I'm a bit unsure because the charges don't balance

science
if two bumper cars collide and they both stop, how do you know a force has acted on them?

Literature:)
37.4% of marriages end up in divorce. these are mostly young people, about 20's.

Nutrition of the young child
B, i think

Economics
705 3987.5

Literature (If considered that)
Ms. Sue is right. 37.4% of marriages end up in divorce.

literacy
The first word and all the other words after it besides the, on, and, and other commonly used words. For example: "The City Charlotte is on the Map!"

social studies
In the year 1900 how many colleges were there?

math
a box holds 23 puzzles. How many boxes are needed to hold 238 puzzles?

math
You are having a pool party and invite 2 of your best friends. These two friends each invite two other people. Each of these 2 people invite 2 people that haven't been invited. How many people will be invited if this process continues for four rounds?

math
20.5092

math
A jacket Jason wants to buy is priced at \$18.99. The sales tax is 8%. What is the total cost of the jacket, including tax?

circuits
the zero input response of a series RLC circuit with R=80 ohms is V(c)=2e^(-2000t)cos(1000t)-4e^(-2000t)sin(1000t) V for t>0 if the initial conditions remain the same, what is the zero-input response when R=40 ohms

circuits
in a parallel RLC circuit you have L=100mH and i= inductor current i=50e^(-4000t)-10e^(-5000t) mA how do you find R and C??

math
how do you find the coordinates of the point (x, y, z) on the plane z = 1 x + 1 y + 2 which is closest to the origin

math
Find the maximum and minimum values of f(x,y)=xy on the ellipse 8x^2+y^2=4?????

math
Find three positive real numbers whose sum is 52 and whose product is a maximum?????

What relationship exists between high tides and phases of the moon?

Chemistry
Write balanced equations for the formation of [Ni(NH3)6][BF4]2 starting from an anhydrous sample of nickel(II) choride hexahydrate. (3 equations necessary) I am slightly confused by this. I think the starting sample has the formula [Ni(H20)6]Cl2 Would this react with ammonia...

Chemistry
I think that nickel(II) nitrate has the formula Ni(NO3)2. As we are starting from anhyrdrous nickel nitrate I thought the first step might be to hydrate it Ni(NO3)2 + 6H2O --> [Ni(H2O)6](NO3)2 and then I thought a reaction with potassium thiocyanate KSCN but I am not sure ...

Chemistry
Write balanced equations for the formation of K4[Ni(NCS)6] starting from an anhydrous sample of nickel(II) nitrate. (3 equations necessary)

Chemistry
What is a balanced equation for the formation of [Co(NH3)5Cl]2+ from [Co(NH3)5(OH2)]3+ ?

Math
Which 3 x 3 matrix represents a reflection in the yz plane followed by inversion through the origin?

trig!!
Sin(X-y)sin(x+y)=sin^2 x - sin^2 y work on one side only...so i worked on the right =(sinx-siny)(sinx+siny) does that equal sin(x-y)sin(x+y)??? help!

Trig
Sin(X-y)sin(x+y)=sin^2 x - sin^2 y work on one side only...so i worked on the right =(sinx-siny)(sinx+siny) does that equal sin(x-y)sin(x+y)??? help!

Chemistry
What would be the molality of a solution made up of 75cm^3 of water and 0.21 g of NaCl?

math
body of mass 7 kg moves in a (counterclockwise) circular path of radius 4 meters, making one revolution every 13 seconds. You may assume the circle is in the xy-plane, and so you may ignore the third component. how do you find the centripetal force acting on the body how do ...

math
A gun has a muzzle speed of 90 meters per second. What angle of elevation should be used to hit an object 180 meters away? Neglect air resistance and use 9.8m/s^2 as the acceleration of gravity.

math
how do you find the curvature k(t) of the curve r(t)=(-2sint)i+(-2sint)j+(-4cost)k?

writing
What should I write my narrative poem about that will make my class laugh? There has to be 4 stanzas and each have to have 3 lines.

Chemistry
What is the pH of a solution made up of 50cm^3 of 1M Ethanoic Acid and 25cm^3 of 1M sodium ethanoate? Assume Ka for Ethanoic acid is 1.8 x 10^-5 mol dm^-3 I'm not quite sure how to do this. I was going to use the equation pH = pKa + log[A-]/[HA] but it doesn't seem to ...

math
Tank 1 initial contains 70 L (liters) of water and 450 g of salt, while tank 2 initially contains 20 L of water and 200 g of salt. Water containing 10 g/L of salt is poured into tank1 at a rate of 1 L/min while the mixture flowing into tank 2 contains a salt concentration of ...

Spanish
What does Pablo Neruda refer to in the last verse of his poem "La Anaconda Copper Mining Company"? "Y hay una y otra cruz torcida en las laderas infernales como única leña dispersa del árbol de la minería."

What is domain?

What is domain?

Maths
A particle rotates in a circular orbit about a point located 30cm away, with angular speed 2 rad s^-1. If the angular momentum is 0.2 Js, determine the mass of the particle. I used L=mr^2 omega and got 1.11kg A constant torque of 0.2Nm accelerates the particle for 5s. ...

math
how do you find the differential equation for t(dy/dt)+9y=8t and y(1)=6?

math
how do you find the function to satisfy y'-2y=2e^(3t) and where y(0)=-5?

math
how do you find the solution to (dy/dx)+ycos(x)=6cos(x) when the initial conditions y(0)=8? all i can get is y(x)=e^sin(x) + 7

social studies
What from nature might have given the Egyptians the belief that they would have life after death?

Chemistry
The cell Pt|H2(1 bar)|HCl(m)|AgCl(s)|Ag has an Stadard elctrode potential value of 0.2224V at 298K Using the Nernst equation, calculate a value for the EMF when the HCl concentration is 0.20M. I know what the Nernst equation is but I am unsure how to use it when I only have ...

math
How do you find the area of irregular figures using 3.14 for pi?

math
How do you find the area for an irregular figure using 3.14 for pi?

english
Say one of the funniest moments you had in school and tell them why that was so memorable and funny

AP World History
Well we are doing a project on empire building and we had to answer a couple of questions. I looked all over the internet and I can't find answers to these four questions. this is due tomorrow so I'm really desperate. Can someone help me out? My empire is the Spanish ...

Chemistry
One mole of nirtogen at 273K occupying 10 litres (state 1) is to be expanded to a volume of 20 litres at 373K (state 2). An infinite number of paths from state 1 to state 2 are possible. Consider the following important paths: (a) The gas is expanded isothermally and ...

I'm supposed to write a paper on the "real" reason behind not running in the house. It's just why you think you shouldn't run in the house, just something funny nothing real. What should I say is the reason, that will make my class laugh?

Chemistry
A conductivity cell was calibrated using KCl solution (0.01 mol dm^-3) with a conductivity of 0.141 S m^-1 and the resistance was found to be 520 Ohms. The resistance of a saturated solution of silver chloride was found to be 3.8 x 10^5 Ohms. Calculate the solubility product ...

Chemistry
Which phosphates are found in human urine? I am writing about the discovery of phosphorus. I know that after urine was left to stand for several days and boiled to a paste it contained ammonium sodium hydrogen phosphate. Is this a constituent of fresh urine or did a reaction ...

English
Such a person as he/him is.... use "he"or"him"?

Chemistry
What is a definition for i) radial wavefunction ii) angular wavefunction What is the physical meaning of each?

Chemistry
An ammonium halide A contains 9.664% nitrogen. Identify A.

math
How else can you write x^2+4x-15?

calculus
this is part of calculus cause i need it to find critical points of a graph

calculus
solve 4x^3-6x+2=0 for all x

Math
Find the stationary points of function E(a,b) = a^4 - 2a^2 + 2b^2 and classify each of these as either a minimum, maximum or saddle point.

Chemistry/Math
No, I can't find one for a second order reaction.

Chemistry/Math
Write a differential equation describing a second order reaction – a reaction in which the rate of depletion of the concentration of the reactants depends on the square of reactants’ concentration. Solve this differential equation and hence find an expression for the...

Math
Find the specific solution for the following differential equations: a) (dy/dx)^2 - x^4 = 0 given the initial value y(1) = 0 b) dy/dx = ysinx given the initial value y(pi) = 1

Maths
P=(2J+1)exp(-(BJ(J+1))/kT) where B, k and T are constants a. Show that dP/dJ=(2-(B(2J+1)^2)/kT)exp(-BJ(J+1)/kT) b. Show that P exhibits a maximum and determine the expression for Jmax c. Find the value of P when J=0 and the limiting value of P when J becomes large(infinity).

physics
Ok, I am not sure how to about about solving this problem and have been staring at it and drawing pictures for several hours now. Do I use the spring equation for potential energy? Or is it a momentum problem where I should assume the spring has it's own velocity? Any help...

Maths
I think to plot it as a straight line you would plot logy on the y-axis against logx on the x-axis, but I'm not sure.

Maths
Transform the following relationships/funtions into linear form and identify expressions for the x and y variables. a) (x^2/a^2) + (y^2/b^2) = 1 where a and b are constants. b) k(T) = (kT/h)exp((deltaS)/R)exp(-(deltaH)/RT) where k, deltaS, deltaH and R are constants.

Maths
A(t)=A'e^(-t/r) where A(t) is the amount after time t, A' is the initial amount at t=0 and r is the decay time. Give an interpretation of the parameter r.

Chemistry
Given that for ethanoic acid pKa=4.75, calculate the pH of sodium ethanoate 0.1M.

chemistry
that's what I don't understand! :(

chemistry
a cubic piece of metal measures 5.00 cm on each edge. if the metal is nickel, whose density is 8.90g/cm cubed, what is the mass of the cube?

Chemistry
I have worked out that the element is nitrogen and the first hydride is NH3. I calculated the second hydride to have the empirical formula NH2. Would the molecular formula be N2H6? I'm not too sure about the structures.

Chemistry
Two hydrides A and B of an element X contain 17.76% and 12.58% by mass of hydrogen. Identify A and B and comment on their structures.

algebra 1
simplify 11/12-(1/3+1/4)

Economics
How to explain the differences in prices of "homogeneous" goods among sellers.

English-Accented Syllables
The accented syllable is the syllable in the word that you automatically say louder or more clearly.

year 7 geography
research which instruments are needed to measure which feature of the weather Temperature , Precipitation , Cloud cover , Cloud type , Wind direction , Wind speed , Visibility. The example i have got is visibility - eyes and instruments Does the question mean you have to put ...

Calculus
OK I understand the concept present value but I don't understand how to solve for present value in this context: Assume that you won a local contest for which you gain a continuous income stream at a rate R(t)=5000e^0.1t per year for 5 years and r=0.05. Find present value...

algebra
A certain population of bacteria doubles every 3 weeks. How long will it take for a population of 3,500 to triple?

Caluculus
Can anyone help me with this problem? Suppose that during a controlled experiment, the temperature in a beaker containing some chemical substance at time t is rising at a rate of (15/13)t^2-(7t) degrees centigrade per minute. If the temperature after 1 minute is measured to be...

Spanish homework
Sorry, I made a mistake. INstead of 'When poachers steal the eggs came' it should be 'When poachers come to steal the eggs.'

Spanish homework
Yesterday, I saw Martin Luther sitting on top of a large pumpkin. A cabbage fell from the sky and hit him in the head. Martin Luther was angry and swore at the cabbage. Most people do not know this, but Ralph Waldo Emerson is still alive. He was found buried under a layer of ...

English/Spanish
And "sorry" is triste

English/Spanish
By th wat the Spanish word for 'homework' is tarea

English/Spanish
No matter. If you need to translate it just type it in at Google Translate.

SOCIAL STUDIES
NAME A MONARCHY

Social Studies
OMG I AM SO SORRY I DIDN'T MEAN TO POST THAT ON THIIIS SITE...SORRRYY

Social Studies
WOOOOOOOOOOOOOOOOOOO ...

English
Does anyone know any specific poems or a website with poems that may relate to any of these themes...? - loss of innocence/youth - taking a chance - being yourself - imagination vs. reality any poems relating to these will do! even a poem that is opposite of the theme will be ...

English
2 questions: 1. what is the one poetic device called that's an extended metaphor and can last for mostly all of the entire poem? 2. what is the conceit that the tv shows 'rugrats' and 'family guy' share with regards to biabies and speech????? thanks!

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