# David

Popular questions and responses by David-
## Chemistry

IN my experiment, I was doing a qualitative analysis of Group I and II anions using a flowchart. IN the chart I added 5 drops of 0.1M AgNO3 and several drops of 3M HNO3 to 5 drops of solution and found that a precipitate was formed. Thus it was classified

*asked on April 12, 2009* -
## chemistry

at 20 C the vapor pressure of dry ice is 56.5 atm. if 32 g of dry ice is placed in an evacuated .25 l chamber at a constant temperature of 20 C will all the dry ice sublime

*asked on January 13, 2013* -
## Chemistry

At equilibrium, the concentrations in this system were found to be [N2] = [O2] = 0.100 M and [NO] = 0.500 M. N2(g) + O2(g) 2NO(g) If more NO is added, bringing its concentration to 0.800 M, what will the final concentration of NO be after equilibrium is

*asked on March 5, 2012* -
## physics

A board that is 20 cm wide, 5 cm thick, and 3 m long has a density of 350 kg/m^3. The board is floating partially submerged in water do density 100 kg/m^3. What fraction of the volume of the board is floating above water?;

*asked on July 13, 2013* -
## Physics

A 69.5kg football player is gliding across very smooth ice at 2.15m/s . He throws a 0.470kg football straight forward. A) What is the player's speed afterward if the ball is thrown at 16.0m/s relative to the ground? B) What is the player's speed afterward

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

at 25C and 795 torr, carbon dioxide has a solubility of 0.0356 M in water. What is the solubility at 25 C and 2070 torr? ____ M I know that at a given temperature, the solubility of a gas in a liquid is directly proportional to its pressure but how would

*asked on February 16, 2012* -
## Science

A block and tackle having velocity ratio of 5 is used to raise load of 400N through a height of 10m.If the work done by friction is 1000j.calculate the work done by the effort

*asked on July 26, 2020* -
## statistics

The director of an alumni association for a university wants to look at the relationship between the number of years since graduation and the amount of monetary contribution an alumnus makes to the university. He collects data on 50 alumni who have made

*asked on September 22, 2012* -
## AP Chemistry

Determine the volumes of 0.10 M CH3COOH and 0.10 M CH3COONa required to prepare 10.0 mL of buffer of each of the following pH values? a. Ph 3.7 b. pH 5.7 C. pH 5.7 I just need to see how to do one of them and I'll understand how to do the rest.

*asked on April 22, 2015* -
## Math

in a survey of 290 newspaper readers, 181 of them read the Daily Times, 142 Read the Guardian 117 read punch and each reads at least one of the three papers if 75 read the Daily Times, and the Guardian, 60 read the Daily Times and punch, and 54 read the

*asked on November 11, 2018* -
## Chem

Write a chemical formula. . . Ca2+ and S2-

*asked on July 30, 2016* -
## Chemistry

Given that the vapor pressure of water is 17.54 torr at 20 C, calculate the vapor-pressure lowering of aqueous solutions that are 2.40 m in (a) sucrose, C12H22O11, and (b) aluminum chloride. Assume 100% dissociation for electrolytes. Sucrose Delta P = __

*asked on February 19, 2012* -
## math

Find the smallest positive integer not relatively prime to 2015 that has the same number of positive divisors as 2015.

*asked on June 19, 2016* -
## Math

A bucket begins weighing 15 pounds, including the sand it holds. The bucket is to be lifted to the top of a 50 foot tall building by a rope of negligible weight. However, the bucket has a hole in it, and leaks 0.1 pounds of sand each foot it is lifted.

*asked on April 30, 2016* -
## Physics

A man holds a child on his shoulder while watching a football match.how much work is done if the game lasts for 2hours

*asked on January 18, 2018* -
## math

Raj has a card that he uses to buy lunch at school. Each day he spends the same amount.

*asked on July 20, 2020* -
## chemistry

When the glucose solution described in part A is connected to an unknown solution via a semipermeable membrane, the unknown solution level rises. Based on this information, what can be said about these two solutions? a.) The unknown solution had the lower

*asked on February 24, 2010* -
## Calculus

Project Setup:You work for a company that manufactures cylindrical steel drums that can be used to transport various petroleum products. Your assignment is to determine the dimensions (radius and height) of a drum that is to have a volume of 1 cubic meter

*asked on April 17, 2019* -
## Maths

A student spent 2 /9 of his pocket money on beverage and 1 /4 on books. What? fraction

*asked on November 14, 2017* -
## Physics

A mass m1 = 3.3 kg rests on a frictionless table and connected by a massless string over a massless pulley to another mass m2 = 4.4 kg which hangs freely from the string. When released, the hanging mass falls a distance d = 0.87 m. 1) How much work is done

*asked on September 30, 2012* -
## physics

what is the resistivity of a cylindrical materia wire whose 1.0 length has a resistant of 2.0ohm the diameter of the wire is 0.5mm

*asked on May 6, 2019* -
## english

Identify the subjects of the following sentences. Jacob's favorite poker game is Texas Hold'em

*asked on March 8, 2012* -
## chemistry

How many grams of water would you add to 1.00 kg of 1.48 m CH3OH(aq) to reduce the molality to 1.00 m CH3OH. Use two sig figs. I get 4.8 * 10^2 grams and its not right. I want to put this up here again to see if there are any errors that could have

*asked on February 21, 2010* -
## Chemistry

What is going on in the hexane layer at the end of the Group I anion experiment? (when color of hexane layer is yellow you have Br- and when it is brown or purple you have I-.) please explain

*asked on April 12, 2009* -
## mathematics

A village contains n people.A medical team inoculates m people each day against yellow fever.After four days,how many people still need to be inoculated .

*asked on July 13, 2020* -
## PHYSIC

A body accelerate uniformly from rest at 2ms-2 .calculate it,s velocity after travelling 9m

*asked on October 17, 2018* -
## physics

A copper atom has 29 electrons revolving around the nucleus. A copper ball has 4x10^23 atoms. What fraction of the electrons be removed to give the ball a charge of +9.6uC?

*asked on March 31, 2015* -
## elementary statistics

A statistics professor is used to having a variance in his class grades of no more than 100. He feels that his current group of students is different, and so he examines a random sample of midterm grades (listed below). At 0.05 alpha level can it be

*asked on November 30, 2013* -
## calc help showed work

If the function f has a continuous derivative on [0,c], the the integral(o to c) of f'(x)dx= a)f(c)-f(0) b)absolute value (f(c)- f(0)) c) f(c) d)f'(x)=c e)f"(c)-f"(0) My work: so the the answer to the integral is f(x) and when find the answer from o t0 c,

*asked on December 7, 2006* -
## Biology

Compare and contrast indirect versus direct values of biodiversity, and provide examples.

*asked on October 17, 2014* -
## Pre algebra

A cyclist rides her bike at a speed of kilometers per hour. What is this speed in kilometers per minute? How many kilometers will the cyclist travel in minutes? Do not round your answers.

*asked on April 26, 2014* -
## Geometry

According to the given information, segment AB is parallel to segment DC and segment BC is parallel to segment AD.. Construct diagonal A C with a straightedge. It is congruent to itself by the Reflexive Property of Equality. ________________. Angles BCA

*asked on February 25, 2014* -
## R&slotto pool

What are the possible numbers to play for todays club master lotto pool

*asked on December 20, 2012* -
## Elasticity (Physics)

A tunnel of length L=150m, height H=7.2m, and width w=5.8m (with a flat roof) is to be constructed at a distance d=60m beneath the ground. The tunnel roof is be entirely supported by square steel columns, each with a cross sectional area of 960 cm^2. The

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

A function is defined by f(x) = ax^3 + bx^2 + cx + d. Find a, b, c, and d if f(x) has a point of inflection at (0, 2) and a local maximum at (2,6).

*asked on March 10, 2020* -
## Math

theoretically if you roll a number cube 36 times, how many times would you expect to roll the number one? could you also give me explanation? Thank you. and also answer as fast as possible.

*asked on March 13, 2017* -
## math

In 2 minutes, a conveyor belt moves 300 pounds of recyclable aluminum from the delivery truck to a storage area. A smaller belt moves the same quantity of cans the same distance in 6 minutes. If both belts are used, find how long it takes to move the cans

*asked on December 4, 2012* -
## chemistry

Describe how to correctly prepare 400 mL of 0.6 M NaOH starting from solid NaOH.

*asked on December 8, 2019* -
## Statistics

. Two thousand randomly selected adults were asked whether or not they have ever shopped on the internet. The following table gives a two-way classification of the responses obtained. Have shopped Have never shopped Male 500 700 Female 300 500 Suppose one

*asked on June 11, 2013* -
## Physics

A tortoise and hare start from rest and have a race. As the race begins, both accelerate forward. The hare accelerates uniformly at a rate of 0.8 m/s2 for 4.4 seconds. It then continues at a constant speed for 13.5 seconds, before getting tired and slowing

*asked on August 27, 2012* -
## Physics

Two identical cars are traveling at the same speed. One is heading due east and the other due north, as the drawing show. What is true regarding the kinetic energies and momenta of the cars?

*asked on October 24, 2010* -
## math

Kate used 555 grams of wool to knit a sweater, a hat and a scarf. She used 5 times less grams for the hat than for the sweater. She used 5 grams more for the hat than for the scarf. How many grams of wool did she use to knit each item?

*asked on July 12, 2017* -
## Physics

In a repair shop a truck engine that has mass 429 kg is held in place by four light cables (Figure 1) . Cable A is horizontal, cables B and D are vertical, and cable C makes an angle of 37.1∘ with a vertical wall. Tension in cable A is 729 N . a.What is

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

8-hydroxyquinoline (Q) can complex and precipitate many metals. A mixture of the aluminium and magnesium complexes weighed 1.0843g (MW=459.43; 312.61). When ignited, the mixture decomposed and left a residue of Al203 (MW 101.96) and MgO (MW 40.304)

*asked on August 24, 2014* -
## chemistry

In the reaction N2 + 3H2 -> 2NH3, how many grams of NH3 gas would be formed when H2 gas, having a volume of 11.2 liters at STP, reacts with excess N2 gas? Completly confused, thank you very much for your help :)

*asked on April 6, 2011* -
## physics

Use conservation of energy to determine the angular speed of the spool shown in the figure below after the 3.00 kg bucket has fallen 4.05 m, starting from rest. The light string attached to the bucket is wrapped around the spool and does not slip as it

*asked on April 6, 2016* -
## Statistics

3. The following table gives a two-way classification of all basketball players at a university who began their college careers between 2004 and 2008, based on gender and whether or nor they graduated. Graduated Did Not Graduate Male 126 55 Female 133 32

*asked on June 11, 2013* -
## chemistry

at 20 C the vapor pressure of dry ice is 56.5 atm. if 32 g of dry ice is placed in an evacuated .25 l chamber at a constant temperature of 20 C will all the dry ice sublime

*asked on January 13, 2013* -
## Stats

Question 3 Investment analysts generally believe the interest rate on bonds is inversely related to the prime interest rate for loans; that is, bonds perform well when lending rates are down and perform poorly when interest rates are up. Can the bond rate

*asked on August 20, 2012* -
## Physics

Doubling the voltage across a parallel plate capacitor does not double which of the following? a. the charge b. the electric field between the plates c. the energy stored d. the electric force on the plates e. both a and b is the answer A if not then how

*asked on February 23, 2011* -
## Physics Flux

The electric flux through the surface shown in Figure Ex27.10 is 15.0 Nm2/C, and the electric field makes an angle á = 70° with the surface. What is the electric field strength? The surface is a 10cm by 10cm square.

*asked on September 13, 2010* -
## geometry

When the number w is multiplied by 4, the result is the same as when 4 is added to w. What is the value of 3w

*asked on March 3, 2010* -
## dbs

Determine the rate of interest at which a sum of money will become 216/125 times the original amount in 1 and a half years, if the interest in compounded half

*asked on September 24, 2017* -
## math

Three departments of a company employ a total of 1274 people. The second department employs 70 more people than the first one, and the third department employs 84 more workers than the second one. How many people work in each department?

*asked on July 12, 2017* -
## algebra 2

The amount of money in an account with continuously compounded interest is given by the formula A=Pe^rt , where P is the principal, r is the annual interest rate, and t is the time in years. Calculate to the nearest hundredth of a year how long it takes

*asked on May 27, 2011* -
## Chemistry

A compound on heating gives a crackling sound, a reddish fume, and a gas which relights a glowing splint. the residue is reddish brown when hot and yellow when cold. What are- 1. the compound? 2. the fume 3. the gas 4. the residue?

*asked on July 27, 2010* -
## AP Chemistry

What is the Van't Hoff Factor of MgSO4*7H2O? We're doing a colligative properties lab at my school where we dissolve various amounts of MgSO4 in 100 grams of water. What value/range of values should I expect the Van't Hoff Factor to be?

*asked on December 6, 2014* -
## trig

To the nearest degree, determine the measure of angle X for each value of tan X a. tan X = 0.49 Just not sure how to solve these questions

*asked on October 12, 2011* -
## physics

A mercury thread has 13cm and 24cm at the ice and steam point respectively, fine it temperature when the mercury thread is 19cm long.

*asked on May 17, 2019* -
## math

Team Alpha had one fourth as many people as team Beta. After 6 people quit team Beta and 12 people were transferred to team Alpha from team Beta, both teams became equal. How many people were there originally on team Alpha?

*asked on July 12, 2017* -
## math

Team one had twice as many workers as team two. The number of workers in team one is reduced by 5 and the number of workers in team two is reduced by 2. How many workers are there in each team now if there are 7 more workers in team one?

*asked on July 12, 2017* -
## Maths ( permutation and combination)

a town council plans to plant 12 trees along the centre of a main road.It has 4 hibiscus trees, 6 Jacaranda trees, 2 oleander trees. How many different arrangements of these 12 trees can be made if no hibiscus tree is next to another

*asked on September 25, 2016* -
## CHEMISTRY

A solution of a metal carbonate M2CO3, was prepared by dissolving 7.46 g of the anhydrous solid in water to give 1000cm^3 of solution. 25.0cm^3 of this solution reacted with 27.0cm^3 of 0.100 mol/dm^3 hydrochloric acid. Calculate the relative formula mass

*asked on July 9, 2016* -
## My brain is hurting please help?

At a homeowners' association meeting, a board member can vote yes or on a motion. There are three motions on which each board member must vote. Complete parts (a) through (c) below. (a) Determine the number of points in the sample space.

*asked on June 5, 2016* -
## Chemistry

Consider the reaction: K2S(aq)+Co(NO3)2(aq)=2KNO3(aq)+CoS(s) what volume of 0.255 M K2S solution is required to completely react with 160 mL of 0.130 M Co(NO3)2?

*asked on April 29, 2016* -
## Physics

A particle is moving at 0.75c relative to a lab on Earth. By what percentage is the Newtonian expression for its momentum in error, i.e., how wrong is the classical formula? (The percentage error is the difference between the erroneous and correct values,

*asked on September 20, 2014* -
## Stats

This assignment requires you to use Excel. In question 1, you will use the charting features. In questions 2 and 3, use the regression tool from the analysis toolpack. There is no template for this assignment. Make sure you explain your answers and provide

*asked on August 20, 2012* -
## Math

A rooming house has three rooms that contains four beds, three beds and two beds respectively. In how many ways can nine quests be assigned to these rooms? The book says it is 1260. I have no idea how they got this. I know it requires combinations. Could

*asked on April 16, 2011* -
## 9th grade

Write an algebraic expression for the phrase. the product of g and 4 a.4g b.g + 4 c.g/4 d.g – 4

*asked on September 9, 2010* -
## math

Find an angle between 0 degree and 360 degree that is coterminal with given angle. a. 361 degree b. -100 degree c. 1270 degree

*asked on October 26, 2009* -
## sum geometric series

what is the sum of geometric infinite series 3/2+ 9/16+ 27/128+ 81/1024=.... i know the formula is S=a/(1-r) my teacher, he usually transforms into a formula of the sum series and finds out a and r.but i don't how to do that. the pattern i saw is 3/2 +

*asked on April 9, 2007* -
## chem help

a scuba diver breathing normal air descends 100m of depth, where the total pressure is 11 atm. What is the partial pressure of oxygen that the diver experiences at this depth? Can someone help out on this question? Make a ratio: 11atm/1atm= P/partial

*asked on March 19, 2007* -
## Business Math

Find the ordinary interest to the nearest cent. $19,000 at 12% for 101 days

*asked on February 23, 2015* -
## Statistics

1. The mean monthly mortgage paid by all home owners in a town is $2365 with a standard deviation of $340. a) Using Chebyshev’s theorem, find at least what percentage of all home owners in this town pay a monthly mortgage of (i) $1685 to $3045 & (ii)

*asked on June 11, 2013* -
## Math

Joelle earns her regular pay of 7.50 per hour for up to 40 hours a week. for each hour over 40 hours of work in a week, joelle is paid 1.5 times her regular pay. how much does joelle earn for a week in which she works 42 hours?

*asked on August 14, 2012* -
## finance

Adams Enterprises’ noncallable bonds currently sell for $1,120. They have a 15- year maturity, an annual coupon of $85, and a par value of $1,000. What is their yield to maturity?

*asked on February 27, 2011* -
## physics

A string has a linear density of 8.5*10^-3 kg and is under the tension of 280 N. The string is 1.8 m long, is fixed at both ends, and vibrating in the standing wave pattern. What is the speed, length, and frequency?

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

A 52 g mountain climber, start from rest, climbs a vertical distance of 730 m. At top, she is again at rest. In the process, her body generates 4.1*10^6 J of energy via metabolic processes. Her body acts like a heat engine with efficiency ( W/Q_h.) W is

*asked on November 18, 2010* -
## CHECK MY CHEMISTRY WORK PLEASE ASAP

1. You have been given a sample of unknown molarity. Calculate the molarity of a solution which has been prepared by dissolving 8.75 moles of sodium chloride in enough water to produce a solution of 6.22l. 2. You have a sample which consists of 428g sodium

*asked on January 10, 2017* -
## Geometry

If the width and height of a rectangular prism are each shrunk to one seventh of the original size but the length remains the same, what is the formula to find the modified surface area?

*asked on June 20, 2016* -
## Physics

Two forces act on a 55-kg object. One force has the magnitude 65 N directed 59 clockwise from the positive x-axis, and the other has a magnitude ofm35 N at 32 clockwise from the positive y axis. What is the magnitude of acceleration?

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

Eggs of Amphioxus is : (a)alecithal (b)telolecithal (c)meiolecithal (d)mesolecithal is it A ?

*asked on September 23, 2010* -
## Chemistry

Determine whether a solid forms when solutions containing the following salts are mixed. (Express your answer as a chemical equation. Identify all of the phases in your answer) NaF and AgNo3 MnSO4 and Na2CO3

*asked on May 24, 2010* -
## Math

Find the value(s) of x, so that f’(x) = 0 for the function f(x) = 4x3 – 6x2 – 24x.

*asked on April 1, 2010* -
## chemistry

An ideal liquid solution has two volatile components. In the vapor in equilibrium with the solution, the mole fractions of the components are (a) both 0.50; (b) equal, but not necessarily 0.50; (c) not very likely to be equal; (d) 1.00 for the solvent and

*asked on February 20, 2010* -
## math

A woman 5 ft tall is standing near a street lamp that is 12 ft tall. Find a function that models the length L of her shadow in terms of her distance d from the base of the lamp.

*asked on October 9, 2009* -
## finding c: calc

let f(x)=square root x. if the rate of change of at x=c is twice its rate of change at x=1, then c=? what???? i don't get get it. to begin with, i took the derivative if that helps which is 1/(2*sqrtx) . f'(x) = 1/(2*sqrtx) is correct f'(x=1) = 1/2 The

*asked on December 5, 2006* -
## Geometry

You roll a six-sided die. Event A: Roll an odd number. Event B: Roll a number less than 5. Find P (A or B) . Express you answer as a fraction in simplest form. Plz help!!

*asked on November 19, 2019* -
## Math

It costs a bus company 225$ to run a bus on a ski trip, plus 30$ per passenger. The bus has a seating capacity of 22 passengers. The company charges 60$ per fare if the bus is full. For each empty seat, the company has to increase the ticket price by 60$.

*asked on January 14, 2019* -
## Calculus

Find dy/dt at x = 1 and y = x2 + 3 if dx/dt = 4 I'm not sure how to set up this type of equation. Do you use the pythagorem theorem for this? Then take the derivative, and then plug in?

*asked on April 14, 2018* -
## calculus

Find the constant a such that the function is continuous on the entire real line g(x)=x^2-a^2/x-a if x doesn't equal a 6 if x=a

*asked on June 25, 2017* -
## Chemistry

1. You have been given a sample of unknown molarity. Calculate the molarity of a solution which has been prepared by dissolving 8.75 moles of sodium chloride in enough water to produce a solution of 6.22l. 2. You have a sample which consists of 428g sodium

*asked on January 10, 2017* -
## Algebra

the approximate distance, S, in feet that an object falls in t seconds when dropped from a height can be found by using the formula S=16t^2. How long will the object have fallen in 8 seconds?

*asked on July 11, 2015* -
## english

Write a narrative essay that ends with 'once beaten, twice shy'

*asked on January 13, 2015* -
## Physics

The speed of the head of a redheaded woodpecker reaches 3.4 m/s before impact with the tree. The mass of the head is 0.060 kg and the average force on the head during impact is 5.0 N. a)Find the acceleration of the head (assuming constant acceleration) (b)

*asked on January 27, 2013* -
## math

Find the standard deviation for the data. Round your answer to one more decimal place than the original data. {15,13,31,42,58,78}

*asked on September 3, 2010* -
## math

A young man spent 1/4 of his allowance on a movie. He spent 11/18 of the remainder on after-school snacks. Then from the money remaining, he spent $3.00 on a magazine, which left him 1/24 of his original allowance to put into savings. how much of his

*asked on October 7, 2009* -
## English

from "The Mouse" What do Theodoric's attempts to dislodge the mouse represent? A. his acceptance of the idea that being comfortable is more important than being fashionable B. his acceptance of the idea that people should never expose their undergarments

*asked on June 5, 2020* -
## geography

What is the local time of a place on longitude 64 degree east when the GMT is 10•00 am

*asked on January 11, 2020* -
## Chemistry

Which of the following are Arrhenius bases? (a) H3AsO4 (b) Ba(OH)2 (c) HClO (d) KOH Which of the following are Arrhenius bases? (a) CH3COOH (b) HOH (c) CH3OH (d) H2NNH2

*asked on January 6, 2019*