# Posts by SARA

Total # Posts: 4,532

**Chemistry**

What volume of 0.123 M NaOH(aq) must be added to 125 mL of 0.197 M H2SO3(aq) to reach the following points? (a) the first stoichiometric point (b) the second stoichiometric point

**Chemistry**

What volume of 0.123 M NaOH(aq) must be added to 125 mL of 0.197 M H2SO3(aq) to reach the following points? (a) the first stoichiometric point (b) the second stoichiometric point

**physics**

12

**CALCULUS**

Find the gradient and directional derivative of f at P in the direction of v: f(x,y)=ln(x^2 + y^2 +1)+ e^(2xy) P(0,2) v=5i-12j

**Calculus - HELP plz!**

Find all of the first partial derivatives of f(x,y,z)=arctan y/xz

**vectors**

why are the answers in the back of my textbook,[3,4,-1], [4,5,-5], [2,3,3]

**vectors**

find three points on each plane [x,y,z]= [3,4,-1]+s[1,1,-4]+ t[2,-5,3]

**physics**

a horizontal force of 600Npulls two masses 10kg lying on a frictionnnnless surface connected by a light string .what is the tension in the string?Does the answer depend on which mass end the pull is applied

**physics**

explai biot-savart,law.an electron with velocity 3*107ms1 describe a circular path in a uniform magnetic field of 0.2T,perpendicular to it.calculate the radius of path

**math**

at a certain factory each worker either drives to work or take the bus. the ratio of worker who take the bus to those who drive to work is 2:5. if 120 worker drive to work how many workers are there at the factory?

**Physical Science**

my dear , how did you get this formula of KE, KE=mv2/2 and the mass is equal to (rho)(volume ) so KE=(RHO)(VOLUME)(V2)/2 ,, I confused , can you explain more please

**Physical Science**

Thank you

**Physical Science**

- What is the kinetic energy ,KE, per unit volume V of blood that has a speed of 0.5 m/s. Take density ofƒâblood = 1.0x103kg/m3

**Microbiology**

How can lab practices and safety precautions help reduce hazards in a lab setting? How do you handle blood cultures and pathogenic strains in a lab to minimize contamination?

**maths**

Consider the following system of inequalities: {(c−1)x^2+2cx+c+4≤0 cx^2+2(c+1)x+(c+1)≥0 The sum of all real values of c, such that the system has a unique solution, can be written as ab, where a and b are coprime positive integers. What is the value of a+b? ...

**statistics**

the probability that a house in an urban area will develop a leak is 5%. if 23 houses are randomly selected, what is the probability that none of the houses will develop a leak?

**Chemistry**

What is the pH of a solution of 40.0 ml of 0.800 M HCl titrated with 4.00 ml of 1.00 M Hydroxyl amine?

**Physics :(( help please TT**

thanxxxxxxx hero.........

**chemistry**

how many gram of h2 needed to react with 3.10 n2

**chemistry**

how many gram of h2 needed to react with 3.10 n2

**PHYSICS**

The only force acting on a particle is conservative force F. If the particle is at point A, the potential energy of the system associated with F and the particle is 39 J. If the particle moves from point A to point B, the work done on the particle by F is +25 J. What is the ...

**science**

idfk

**CALCULUS-plz help!**

For the curve r = 2 sin 3(theta): Find the arc length of one petal

**CALCULUS-plz help!**

For the curve r = 2 sin 3(theta): Find the arc length of one petal

**Math**

I think I figure it out. The answer is: 12 A ^2 * 2 A * - 31 + 4 A * 6 + / I figured that that the square sign and the number 2 count as one operator. For ^2 I just use the x^2 button on the calculator and it gave me the same answers.

**Math**

I need to change this expression to postfix form. (12*A^2-2*A+31)/(4*A+6) I know how to do this except for the squaring part. I got stuck. This is my try. 12 A 2 ^ * 2 A * - 31 + 4 A * 6 + / When I test this in a calculator, it gives different results. Another problem is that ...

**biology**

i am researching an article and am having trouble understanding the title. can someone please explain to me in simple terms: Deficiency of a Beta-arrestin-2 signal complex contributes to insulin resistance. so what is a beta arrestin 2 signal complex?

**Chemistry**

radioactive sodium chloride is appropriate for diagnosing circulatory problems, but radioactive xenon is helpful in searching for lung problems. Explain why. I understand different elements are used for specific parts of the body but I don't understand this question. ...

**physics**

A 22.0 Ω, 11.0 Ω, and 6.00 Ω resistor are connected in parallel to an emf source. A current of 6.00 A is in the 11.0 Ω resistor.What is the potential diﬀerence across the source? Answer in units of V

**commerce**

cn u please help with core business activities of absa nedcor anglo american

**physics**

An 8.0 Ω resistor and a 4.0 Ω resistor are connected in series with a battery. The potential diﬀerence across the 4.0 Ω resistor is measured as 9 V. Find the potential diﬀerence across the battery.

**chemistry**

A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH = 10.23 solution.

**chemistry**

The Ka of a monoprotic weak acid is 7.25 × 10-3. What is the percent ionization of a 0.167 M solution of this acid? If the concentration is more than 1000 times greater than the Ka, then you can make an assumption that simplifies the algebra needed to solve the problem. ...

**chemistry**

The half-equivalence point of a titration occurs half way to the end point, where half of the analyte has reacted to form its conjugate, and the other half still remains unreacted. If 0.460 moles of a monoprotic weak acid (Ka = 3.8 × 10-5) is titrated with NaOH, what is ...

**chemistry**

A flask contains 0.342 g of acid and a few drops of phenolphthalein indicator dissolved in water. The buret contains 0.120 M NaOH. 20.f mL of base is needed to reach the endpoint of the titration. Assuming that the acid is monoprotic, what is the molar mass?

**childhood edu**

One of Rudolph Dreikur's contributions to the field of early childhood education is his belief that? A. All behavior is goal directed. B.There's a difference between behavior and misbehavior I think it's A,am I correct

**math**

solve the problem A drug is injected into a patient and the concentration of the drug is monitored. The drug's concentration, C(t), in milligrams after t hours is modeled by C(t) = (7t)/2t^2+4.

**epidemiology**

Let’s say you are a health policy expert and you are sitting in your office and you receive a phone call from a news reporter. The reporter asks you to comment for a story she is writing. She has learned from the chief of neurosurgery at Cooper University Hospital that ...

**epidemiology**

In a study examining associations between level of education and response to the Philadelphia Public Health Department’s emergency messages to “shelter in place” (meaning stay in your home) following an accidental release of chemicals from the Sunoco refinery in...

**epidemiology**

) In a recently published article authors reported on their research examining the effectiveness of compound C-4277, an anti-viral agent. This agent was tested to determine its impact on rhinoviruses, which are the leading cause of common colds. The article states that 1,800 ...

**chemistry**

I mean the head temp. is the higher temp., they called it like this in my university. anyway,this question in the dehydration of cyclohexanol. when we do elimination the heat temp. should be kept below 90 c, why?

**chemistry**

why is the head temperature kept below 90 c in the initial step of the dehydration reaction?

**Calculus-PLZ HELP! =)**

does the sum 3/(2^(n)-1) converge or diverge? n=1--->infinity

**Calculus II**

Is the series 1/(n(n+1)) convergent? n=2 to n=infinity

**Calculus II**

Does 3/(2^(n) +1) diverge or converge in an infinite sum?

**Chemistry**

Nvm figured it out

**Chemistry**

Why is the last step is convert to pH? We are trying to find the hydroxide-ion concentration?not the pH

**Chemistry**

what is the hydronium-ion concentration in a 0.35m solution of NaCO3? For carbonic acid, Ka1=4.2x10^-7 and Ka2=4.8x10^-11. (Kw=1.0x10^-14)

**Chemistry**

I don't press the E button i press the 10^x Button but when I divided the kw/Kb it gives me 2.083x10^-28

**Chemistry**

I plug in the numbers put it doesn't match any of the choices.... I get 4.81x10^-29 The choices are A)2.3x10^-35 B)6.4x10^-23 C)7.3x10^-16 D)48 E)491 Please help!!

**Chemistry**

What is Kc for the following equilibrium? For phosphoric acid, Ka1=6.9x10^-3, Ka2=6.2x10^-8 and Ka3=4.8x10^-13 HPO4^-2 + OH^- <==> PO4^-3 + H2O

**physics**

Calculate the magnitude of the gravitational force between the Earth and an m = 6.00 kg mass on the surface of the Earth. The distance to the center of the Earth from the surface is 6.37×103 km and the mass of the Earth is 5.98×1024 kg. B)Calculate the magnitude of...

**english**

complete the sentence please! a kite___ tries to catch a falling kite before it lands.

**chemistry**

How many mL of 0.40M NaOH are need to neutralize 30.0 mL of 0.50 M H2SO4 according to the following reaction. 2NaOH(aq) + H2SO4 (aq)----Na2SO4 (aq) + 2H2O(l)

**English**

Which senses are appealed to in these lines from Macbeth? Nay, had I pow'r, I should / Pour the sweet milk of concord into hell, / Uproar the universal peace… A. smell, taste, and touch B. hearing, sight, and smell C. sight, taste, and hearing D. hearing, taste, and ...

**Childhood**

Thanks :)))

**Childhood**

Two most common aspects of malnutrition in the u.s are: a) heart disease and obesity b) iron deficiency and heart disease c) dental decay and iron deficiency d) obesity and dental decay. I chose c) dental and iron deficiency is that right?

**curriculum development**

I'm using notes and Internet not text, I can't find much info

**Childhood**

The fundamental purpose of early childhood education should be to a) prepare children for continuing later success in elementary school. B) foster growth of developmental sequences c) foster competence in dealing with life .is letter c) correct?

**Chemistry**

I could use some help please. Ammmonia, NH3, can be made by reacting Nitrogen with Hydrogen. N2+3H2=2NH3 How many moles of NH3 can be made if 7.5 moles of H2 react eith enough N2? Thank-you in advance for any help

**College algebra**

Find the value of f(x) = -3x^2 + 12x-8

**Find the following inequality**

Find the following inequality. 15(x^2-1)>16x

**accounting**

13. A drawback to using _______ when inventory costs are rising is that the company reports lower net income. A. LIFO B. FIFO C. specific-identification costing D. average costing 14. The balance sheet format that lists assets

**Math**

what is a model that shows 180 divided by 9

**MATH**

There is a slide in the park that is 18 feet long. The ladder to the top of the slide is 7.5 feet long. If the ladder and the slide are perpendicular, what is "D", the distance from the top of the slide to the ground? Explain how you got your answer.

**math**

There is a slide in the park that is 18 feet long. The ladder to the top of the slide is 7.5 feet long. If the ladder and the slide are perpendicular, what is "D", the distance from the top of the slide to the ground? Explain how you got your answer.

**math**

2x+3y=13 5x+2y=16

**Math**

If you have 36ft of fencing what are the areas of the different rectangles you could enclose with the fencing? Consider only whole number dimensions.

**chem**

Calculate the pH of a solution made by adding 3.20 g of lithium oxide (Li2O) to enough water to make 1.210 L of solution. (Kw = 1.0 10-14)

**chemistry**

i did what you told me to and had to use the quadratic and got 1.430e-6 for the OH- but it was wrong. is that what you got?

**chemistry**

Calculate the hydronium ion concentration and pH in a 0.037 M solution of sodium formate, NaHCO2. hydronium ion concentration i don't understand these

**chem**

select the stronger base. how do i know this? 1.SeO42− or SO42− 2.BrO− or BrO2−

**physics**

Jacob found a piece of a broken glass bottle. He picked it up and made these observations about it: 1. No color (clear) 2. Makes scratches on wood 3. Has a bumpy surface 4. Broke when I dropped it He thinks the glass is a solid and most of his observations could only apply to ...

**physics**

Jacob found a piece of a broken glass bottle. He picked it up and made these observations about it: 1. No color (clear) 2. Makes scratches on wood 3. Has a bumpy surface 4. Broke when I dropped it He thinks the glass is a solid and most of his observations could only apply to ...

**Physics**

A 1200.0-kg car speeds up from 16.0 m/s to 20.0 m/s. How much work was done on the car to increase its speed?

**chemistry**

Calculate the molar concentration of OH− ions in an 1.79 M solution of hypobromite ion (BrO−; Kb = 4.0 10-6).

**Math...I think...**

A building casts a shadow 54 feet long at the same time a 6 foot tall man casts a shadow 4 feet long. How tall is the tree?

**Finance**

CAN SOMEONE PLEASE PLEASE HELP ME WITH A FINANCE QUESTION THAT I POSTED YESTERDAY,WEDNESDAY,FEB 27TH @ 5:58PM.PLAEASE,ANY AND ALL HELP WILL BE GREATLY APPRECIATED

**physics**

a chinook salmon

**physics**

a moving walkway at an airport has a speed v1 and a length l. a woman stands on the walkway as it moves while the man in a hurry to reach his flight walks on the walkway with a speed of v2 relative to the moving walkway. how long does it take the woman to travel the distance l.

**social studies**

what injuries did they get in the lowell Massachusetts textile mills ? what did the implorers do about it ?

**Finance**

Please help me,math word problems make my brain go crazy. Some friends are urging you to chip in with them to buy a vacant parcel og land on the outskirts of your city. A one-fourth interest would cost you $10,000.Total annual expenses on the property are $2,200.When the ...

**statistic**

At a party there are 33 students over age 21 and 22 students under age 21. You choose at random 3 of those over 21 and separately choose at random 2 of those under 21 to interview about attitudes toward alcohol.. You have given every student at the party the same chance to be ...

**o.chem**

how would doubling the concentration of the nucleophile affect the rate of an sn2 reaction?

**calc 2**

A computer takes 2 seconds to compute a particular definite integral accurate to 4 decimal places. Approximately how long does it take the computer to get 12 decimal places of accuracy using each of the LEFT, MID, and SIMP rules? Round your answers to one decimal place. (a) ...

**chemistry**

how is it possible for the same element to be oxidized in one reaction and reduced in another?

**medical physics**

Rx = 3000 cGy in 10 fractions, whole brain Rt and Lt laterals, KD Siemens 6x. The collimator is set for 22 X 16 cm2 portal films at 92.5 cm SSD. Calculate the treatment port MU to isocenter. Calibration performed std. SAD; treatment performed SSD (assume SSDs at the calc point...

**calculus!!!**

Find the integral of: 2xsqrt(x+1) dx

**calculus**

Find the integral of: (x+2)/(x^3+2x^2-3x)dx

**math**

If a person runs 5 miles in 1 hour, how far will they run in 5 minutes?

**math**

) The circle graph below gives the inventory of the women's department of a store. Coats $49,737 Dresses $47,208 Skirts Lingerie $9273 $5058 Slacks Socks $15,174 Blouses $2529 $5901 What is the total inventory?

**Finance**

Would anyone be able to help me out please? You buy 100 shares of XYZ at $40per share.XYZ pays an annual dividend of $2 and offers an automatic dividend reinvestment plan.Assume that the dividend will remain constant over the next 5 yrs and that the stock will increase 5% each...

**Life orientation**

Hi Sello.I worked in management for yrs so I hope this helps you. There is several laws protecting the employee in the work force. 1]The Federal Civil Rights Act of 1964 prohibits employers from discriminating against job seekers and employees on the basis of race,religion,sex...

**Finance**

I've posted this question once already and really need help. You buy 100 shares of XYZ at $40 per share.XZ pays an annual dividend of $2.00 and offers an automatic dividend reinvestment plan.Assume that the dividend will remain constant over the next 5 years and that the ...

**Financial**

You buy 100 shares of XYZ at $40 per share.XYZ pays an annual dividend of $2 and offers an automatic dividend reinvestment plan.Assume that the dividend will remain constant over the next 5 years and that the stock will increase 5% each year.How much will your XYZ investment ...

**Chemistry**

The solubility of nitrogen in water is 6.9 x 10^-4 at exactly 1 atm pressure. What is the solubility of nitrogen under .80 atmp pressure? I don't know where to start with this problem, what formula do I use?

**Algebra**

54

**chemistry**

how would that help trying a new solvent? i don't understand why the recovery would be so poor, do you know?

**chemistry**

a student dissolves 80 mg of a crude product in 4.5 mL( the minimum required) of methanol at 25 deg C . She cools the solution in an ice bath and obtains crystals. The crystals are recovered by filtration and rinsed with 0.5 mL of ice-cold methanol. After drying, the weight of...

**calculus**

Find the integral of (tan x)^2 sec(x)dx