# 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?????

**6th grade Science**

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."

**8th grade**

What is domain?

**8th Grade Math (Algebra1)**

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 ...

**6th grade**

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!