Thursday

January 29, 2015

January 29, 2015

Number of results: 39,092

**statistics**

2. Assume that the population proportion of adults having a college degree is 0.35. A random sample of 200 adults is to be selected to test this claim. A) What is the shape, mean, and standard deviation of the sampling distribution of the sample proportion for samples of size ...
*August 17, 2010 by Natasha*

**Chemistry**

A 100 mL sample of 0.10M HCl is mixed with 50mL of 0.10M NH3 (Kb=1.8x10^-5). What is the resulting pH?
*April 12, 2012 by Sydney*

**Chemistry**

A 100 mL sample of 0.10M HCl is mixed with 50mL of 0.10M NH3 (Kb=1.8x10^-5). What is the resulting pH?
*April 12, 2012 by Sydney*

**Chemistry**

You have 3.00 L of a 2.37 M solution of NaCl(aq) called solution A. You also have 2.00 L of a 2.00 M solution of AgNO3(aq) called solution B. You mix these solutions together, making solution C. Calculate the concentration (in M) of Na+ ions in solution C.
*May 6, 2011 by tina*

**Chemistry**

An 80.0 g sample of a gas was heated from 25 degree C to 225 degree C. During this process, 346 J of work was done by the system and its internal energy increased by 7495 J. What is the specific heat of the gas? J/(g∗C)
*October 22, 2013 by Nate *

**chem**

A 6.75-g sample of gold (specific heat capacity = 0.130 J/g °C) is heated using 55.8 J of energy. If the original temperature of the gold is 25.0°C, what is its final temperature?
*March 14, 2013 by dave*

**CHEMISTRY**

Suppose you are studying coordination compounds of Co(II) with the ligand pyridine (py, C5H5N, molar mass=79.10). You isolate a crystalline compound, and because the only available anions are Cl- and NO3-, you hypothesize that the empirical formula of the coordination compound...
*May 30, 2013 by PreMed33*

**Chemistry**

When a sample of I2(g) (0.07249 mol/L) is placed in 130.0 L reaction vessel at 865.0 K and allowed to come to equilibrium the mixture contains 0.1110 mol/L of I(g). What concentration (mol/L) of I2(g) reacted? I2(g) = 2I(g)
*October 4, 2013 by plzprovidetheanswer*

**physical science**

If a sample emits 1000 counts per second when the detector is 1 meter from the sample, how many counts per second would be observed when the detector is 2 meters from the sample?
*April 29, 2013 by Denise*

**algebra2**

find the margin of error for the sample proportion, given a sample size of n=1400. Round to the nearest percent.
*May 12, 2008 by jerson*

**algebra**

find the margin of error for the sample proportion, given a sample size of n=1400. Round to the nearest percent.
*May 12, 2008 by jerson*

**help please**

find the margin of error for the sample proportion, given a sample size of n=1400. Round to the nearest percent.
*May 12, 2008 by jerson*

**science**

A sample is composed completely of gold, absolutely free of impurities. Which term or terms could be used to describe this sample?
*September 14, 2008 by jug*

**statistics**

A random sample of n = 30 is drawn from a population that is normally distributed, and the sample variance is s©÷ = 41.5. Use ¥á = 0.05 in testing ¥Ç₀ : ¥ò©÷ = 29.0 versus ¥Ç©û : ¥ò©÷ ¡Á 29.0
*August 12, 2009 by Marianne*

**statistics**

Find the sample variance s2 for the following sample data. Round your answer to the nearest hundredth. x: 23 17 12 35 29 a. 84.20 b. 67.36 c. 101.00 d. 88.84 e. 126.25
*August 20, 2010 by karen*

**chemistry**

a radioactive material is undergoing nuclear decay. After 40 minutes, 25% of the sample remains. What is the half-life of the sample
*August 27, 2011 by marjani*

**chemistry**

A scientist collects a sample of carbon dioxide that contains 1.5 x 1025 molecules of CO2. In grams, what is the mass of the sample?
*December 20, 2011 by Antonio*

**calc**

At what rate is the amount of material growing if bacteria in a sample increases to 250 when the sample is observed for 150 minutes?
*June 21, 2012 by kris*

**Chemistry**

Sample has 150 grams, 20 mL, and a density of 7.5 g/mL. If I double my sample size what would those values turn into?
*January 30, 2013 by Jonnnie *

**statistics**

7. Determine whether it is appropriate to apply the Central Limit Theorem for Proportions: sample size 35, sample proportion 0.95. A) Yes B) No
*May 8, 2013 by ali awan*

**chemistry**

a .50 sample if vegetable oil is placed in a calorimeter. When the sample is burned, 18.9 kJ are given off. what id the caloric value, in kcal/g
*February 5, 2014 by Anonymous*

**statistics**

What formula do I use to solve: A sample with a mean of M = 40 and a variance of s2 = 20 has an estimated standard error of 2 points. How many scores are in the sample?
*July 8, 2014 by brenda*

**Statistics**

The following are weights (in lbs) for a sample of 11 baby boys at the age of 18 months: 21.8 22.2 23.4 24.6 25.1 26.7 27.3 28.0 29.8 30.9 31.2 What is the 80th percentile estimate for these sample?
*September 12, 2014 by Aurora*

**statistics**

1. The table below presents data for a sample of people who completed a religious survey. Age Gender Denomination Church Attendance 56 1 7 4 46 2 6 5 49 2 6 5 49 1 1 5 27 2 9 5 51 1 4 2 47 2 2 3 67 1 5 4 49 2 2 6 33 1 12 6 55 2 9 5 40 1 7 5 62 1 8 6 47 2 6 3 56 2 9 5 22 1 10 ...
*September 3, 2012 by Sandra*

**social statistics**

a smoking researcher is interested in estimating the average age when cigarette smokers first began to smoke. Taking a random sample of 25, she determines a sample mean of 16.8 years and a sample deviation of 1.5 years. Construct a 95% confidence interval to estimate the ...
*September 27, 2014 by Kenya*

**Chemistry**

A sample of Ba3(PO4)2 contains 14.5 g of O. How many g of Ba are in the sample?
*April 23, 2012 by anonymous*

**statistics**

A sample of n = 25 scores has M = 20 and s2 = 9. What is the sample standard deviation? a. 3 b. 4.5 c. 9 d. 81
*December 26, 2013 by Lyn*

**statistics**

According to the local real estate board, the average number of days that homes stay on the market before selling is 78.4 with a standard deviation equal to 11 days. A prospective seller selected a random sample of 36 homes from the multiple listing service. Above what value ...
*July 6, 2013 by Anonymous*

**Chemisry**

The amount of I3–(aq) in a solution can be determined by titration with a solution containing a known concentration of S2O32–(aq) (thiosulfate ion). The determination is based on the net ionic equation Given that it requires 32.9 mL of 0.330 M Na2S2O3(aq) to titrate a 30.0-mL ...
*October 1, 2013 by DeJanee*

**statistics**

A population of 200 voters contains 52 Republicans, 128 Democrats, and 20 independents and members of other parties. A simple random sample of 20 voters will be drawn from this population. The expected number of Republicans in the sample is? and The standard error of the ...
*July 26, 2011 by Charlie*

**economatrics**

calculate standard error when sample size is 25, sample mean is 20, sample variance is 8, population mean is 22, population variance is 64
*November 20, 2014 by priym*

**statistics**

The population mean and standard deviation are given. Find the required probability and determine whether the given sample mean would be considered unusual. For a sample of n=36, find the probability of a sample mean being less than 12.2 if M=12 and O=0.95
*November 16, 2010 by Anonymous*

**College Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.66kg of magnesium and 2.56kg of fluorine. A second sample produced 1.25kg of magnesium.How much fluorine (in grams) did the second sample produce?
*January 28, 2013 by Kaycie*

**Stats**

A random sample of two hundred fifteen adults is selected from a certain population of registered voters. Assume the population is 20% democrats. Use a normal approximation to estimate (a) the probability the sample contains exactly 48 democrats, and (b) the probability the ...
*October 21, 2010 by Chris*

**statistics**

IQ scores are normally distributed with a mean of 105 and a standard deviation of 18. Assume that many samples of size n are taken form a large population of people and the mean IQ score is computed for each sample. If the sample size is n=64, find the mean and standard ...
*September 13, 2012 by kimberly*

**General Chemistry**

A 0.484 g sample of impure NH4Br is treated with 25.00 mL of 0.2050 M NaOH & heated to drive off the NH3. The unreacted NaOH in the reaction mixture after heating required 9.95 mL of 0.0525 M H2C2O4 to neutralize. How many grams of NH4Br were in the original sample? What is ...
*July 12, 2013 by <3*

**statistics**

2. The director of admissions at a large university advises students that the cost of textbooks will average more than $300 for a typical semester. A random sample of 80 students enrolled in the university shows a sample mean cost of $315.40 and a sample standard deviation of...
*August 22, 2010 by Elizabeth*

**chemistry**

A 4.691 g sample of MgCl2 is dissolved in enough water to give 750. mL of solution. What is the magnesium ion concentration in this solution?
*October 4, 2010 by nalleli*

**Chemistry**

A 4.379 g sample of MgCl2 is dissolved in enough water to give 750.0 mL of solution. What is the chloride ion concentration in this solution?
*April 14, 2014 by Chris*

**Chemistry**

A 23.596 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 79.504 g of water. A 13.803 g aliquot of this solution is then titrated with 0.1098 M HCl. It required 29.02 ml of the HCl solution to reac the methyl red endpoint...
*November 14, 2011 by Mike*

**chemistry**

A 23.596 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 79.504 g of water. A 13.803 g aliquot of this solution is then titrated with 0.1098 M HCl. It required 29.02 ml of the HCl solution to reac the methyl red endpoint...
*November 14, 2011 by Mike*

**Basic Statistics **

A population of 200 voters contains 52 Republicans, 128 Democrats, and 20 independents and members of other parties. A simple random sample of 20 voters will be drawn from this population. The expected number of Republicans in the sample is ______ ? The standard error of the ...
*July 25, 2011 by mike*

**chemistry**

A sample of an ideal gas at 1.00 atm and a volume of 1.61 L was placed in a weighted balloon and dropped into the ocean. As the sample descended, the water pressure compressed the balloon and reduced its volume. When the pressure had increased to 45.0 atm, what was the volume ...
*April 6, 2012 by catey*

**Chemistry**

AgNO3 + NaCl → AgCl + NaNO3 . How many grams of NaCl would be required to react with 446 mL of 0.211 M AgNO3 solution? Answer in units of grams
*February 21, 2014 by Zoey*

**AP chemistry**

A 28 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 19.5 g. What was the mass of iron in the sample of ore? Answer in units of g.
*August 3, 2010 by Tasha*

**Chemisrty **

A 38 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 11.1 g. What was the mass of iron in the sample of ore? Answer in units of g
*August 31, 2011 by Stoichiometry*

**chemistry**

A 12.8 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 21.3 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 2, 2012 by Emily*

**AP Chemistry**

A 7.6 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 12.9 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 3, 2012 by Rafael*

**AP Chemistry**

A 12 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 27.6 g. What was the mass of iron in the sample of ore? Answer in units of g
*August 29, 2013 by Gabriella*

**AP Chemistry**

A 37.5 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 17.8 g. What was the mass of iron in the sample of ore? Answer in units of g
*September 2, 2013 by Anonymous*

**chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produce 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 3, 2013 by tatianna*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 7, 2013 by Anonymous*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.38kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 7, 2013 by Anonymous*

**statistics**

A random sample of 10 observations has been drawn from a normal population, and the sample variance is found to be s² = 19.5. Determine the 98% confidence interval for ó².
*August 12, 2009 by Laura*

**statistics**

A random sample of n= 12 is drawn from a population that is normally distributed, and the sample variance is s©÷ = 19.3. Use ¥á = 0.025 in testing ¥Ç₀ : ¥ò©÷ ¡Â 9.4 versus ¥Ç©û : ¥ò©÷ > 9.4
*August 12, 2009 by Yadira M*

**Chemistry**

The titration of a sample of a weak acid with an equivalent weight of 108 grams requires 38.2 mL of 0.100 M NaOH. What is the sample mass in mg?
*November 30, 2009 by Telly*

**Chemistry**

10% of a sample reacts in 25 s. If the reaction follows first order kinetics, how long would it take for half the sample to react?
*May 3, 2010 by mandy*

**Statistics**

An urn contains 8 chips, numbered 1 through 8. A sample of 3 is drawn without replacement. What is the probability that the largest chip in the sample is a 5?
*June 24, 2011 by Nicholas*

**statistics**

A sample mean with a z-score value between -1.00 and +1.00 would be considered a fairly typical representative sample. True or False
*October 30, 2011 by Betty*

**chemistry**

An analytical chemist determines that an unknown sample contains 0.3452 mol of LiCl. How many atoms of chlorine does this sample contain?
*December 1, 2011 by jack*

**math**

can someone please explain to me what happens to the mean and standard deviation of the distribution of sample means as the size of the sample decreases?
*February 11, 2013 by kacie*

**Chem**

A 4.96L sample of chlorine gas is contained in a poison control vessel at STP. Calculate the number of grams in this sample
*September 29, 2013 by Joe*

**Chemistry**

A sample of oxygen that occupies 1.00 x 10^6 mL at 575 mm Hg is subjected to a pressure of 1.20 atm. What will the final volume of the sample be if the temperature is held constant?
*November 2, 2014 by Sara*

**Chemistry**

Why is a blank solution used in absorption spectroscopy? I know it is to nullify the reflection, refraction, and diffraction that occurs, but if the blank solution was a dilute solution rather deionized water, how would the concentration of Cr(VI)in a sample be affected?
*February 25, 2014 by Sandy*

**chmeistry**

50 ml of 0.1 M NaCl is mixed with 50 ml of 0.2 M AgNO3 predict whethera ppt of AgCl is formed or not
*April 10, 2010 by Anonymous*

**MATH!**

The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass of the sample. Round your answer to two decimal...
*March 15, 2012 by Kim*

**Chemistry **

Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
*February 25, 2014 by Anonymous*

**Chemistry**

Ascorbic acid (vitamin C) is a diprotic acid having the formula H2C6H6O6. A sample of a vitamin supplement was analyzed by titrating a 0.3252 g sample dissolved in water with 0.0284 M NaOH. A volume of 13.27 mL of the base was required to completely neutralize the ascorbic ...
*February 25, 2014 by PM*

**chemistry**

A 115 mL sample of a 10.0 M ethylene glycol (C2H6O2) solution is diluted to 1.30 L. What is the freezing point of the final solution? (Assume a density of 1.06 g/mL for the final solution.) What is the boiling point of the final solution? How would I go about setting this up? ...
*April 29, 2012 by Jen*

**statistics**

My mean is 175.5 My standard deviation is=90.57 Sample=25 Formula to be used: P(X>190)=P((X-mean)/s sqrt of my sample is = 5 (Which is the square root of 25.)(190-175.5) / 90.57/5) 14.5/18.114 calculator says 0.8004858120790548746825659710721 I check the z-table ...
*May 27, 2013 by Ann*

**statistics **

in the spring of 2001, a university had 40,000 registered students. to estimate the percentage of all students expecting to graduate in 4 years, a simple random sample of 225 students was drawn, 144 of the sample planned to graduate in 4 years. (a) were the draws made with or ...
*May 8, 2014 by anonymous*

**Chemistry**

A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) After 1.27 g of the impure metal was treated with 0.100 L of 0.768 M HCl, 0.0125 mol HCl remained. Assuming the impurities do not react, what...
*September 22, 2013 by James*

**Chemistry**

A sample of 0.30 moles of a metal M reacts completely with excess fluorine to form 18.69 grams of MF2. How many moles of F are in the sample of MF2 that forms? M + F2 ---> MF2 How many grams of M are in this sample of MF2 ?
*July 29, 2011 by Brooke*

**Analytical chemistry**

A 25.0-mL solution of 0.0660 M EDTA was added to a 33.0-mL sample containing an unknown concentration of V3 . All V3 present formed a complex, leaving excess EDTA in solution. This solution was back-titrated with a 0.0450 M Ga3 solution until all the EDTA reacted, requiring 13...
*April 4, 2013 by Ashley*

**analytical chemistry**

Suppose a 4.272 g soil sample undergoes an extraction with 50 ml of extracting solvent to remove the lead. This 50 ml was then diluted to 250 ml and tested by atomic absorption technique. The concentration of lead in this diluted extract was found to be 35.7 ppm. What is the ...
*March 5, 2014 by Lori*

**Chemistry**

Upon decomposition, one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.50 kg of magnesium. How much fluorine (in grams) did the second sample produce?
*October 9, 2012 by Eliza*

**chemistry**

1. If a gaseous sample contains 73% N2 by volume, what is the solubility of N2 in water at 25°C and 1.0 atm (kH in H2O at 25°C = 7.0 10-4 mol/Latm)? 2. Calculate the vapor pressure of a solution of 0.60 mol of cholesterol in 4.5 mol of toluene at 32°C. Pure toluene has a vapor...
*January 31, 2011 by Ashley*

**Statistics**

In an essay of 250-500 words, thoroughly address the following items and respond to the related questions: 1.Define the term standard deviation. Why is it important to know the standard deviation for a given sample? What do researchers learn about a normal distribution from ...
*January 23, 2014 by Andrew*

**chemistry**

Four solution are prepared and mixed together: Start with 100.0ml of 0.100M BaCl2. Add 50.0ml of 0.100M AgNO3. Add 50.0ml of 0.100M H2So4. Add 250.0ml of 0.100M NH4. Write an equation for any reaction that occurs after each step and calculate the concentration of Ba,CL,NO3,NH4...
*May 2, 2012 by Sean*

**college Geol 101**

Suppose you have a sample of clamshell at a Paleoindian site and you measure the 14C activity of a 100-gram sample of carbon as 320 disintegrations per minute (or 3.2 disintegrations per gram of carbon per minute). a.What was the activity (in disintegrations per minute) for ...
*October 20, 2010 by Jay*

**chemistry**

the pressure exerted on a 240.ml sample of hydrogen gas at constant temerature is increased from 0.428 to 0.724.What will the final volume of the sample be?
*October 20, 2010 by shubreet*

**statistics**

assuming a two tailed one sample test is being used,what ie the critical value for t given the following sample sizes. N=10 N=15 N=30
*April 24, 2011 by ryee*

**Math Stats**

A random sample of 30 plants has a sample standard deviation of 3.4 days for maturity. A 95% confidence interval for the population variance is __ to __days.
*March 28, 2012 by Apryl*

**Statistics**

A lottery uses 4 urns containing chips 0 to 9. One chip is selected at random from each urn. How many sample points are in the sample space?
*May 22, 2012 by Tammy*

**chemistry**

A sample of oxygen that occupies 1.00x10^6 mL at 575 mm Hg is subjected to a pressure of 1.36 atm. What will the final volume of the sample be if the temperature is held constant?
*February 27, 2013 by peyton*

**statistics**

True or False A sample mean with a z-score value between 1.00 and +1.00 would be considered a fairly typical, representative sample.
*January 3, 2014 by Lyndyc*

**statistics**

A lottery uses 4 urns containing chips 0 to 9. One chip is selected at random from each urn. How many sample points are in the sample space?
*January 18, 2014 by betty*

**Chemistry**

Suppose you are studying coordination compounds of Co(II) with the ligand pyridine (py, C5H5N, MW = 79.10). You isolate a crystalline compound and since the only available ions are chloride and nitrate, you hypothesize the empirical formula of the coordinaton compound must be ...
*April 20, 2007 by Ray*

**statistics**

a distribution of scores has 6, but the value of the mean is unknown, a researcher plans to select a sample from the population in order to learn more about the unknown mean, if the sample consist of n= 9 scores , how accurately should sample mean represent the population mean
*December 18, 2011 by herry*

**Statistics**

A sample of 12 measurements has a mean of 34 and a standard deviation of 4.5. Suppose that the sample is enlarged to 14 measurements, by including two additional measurements having a common value of 34 each. A. Find the mean of the sample of 14 measurements. Mean = B. Find ...
*April 29, 2010 by Jen*

**Chemistry**

It is possible, although less accurate, to do a standard addition with only one sample. An unknown Fe sample was analyzed by AAS and gave an absorbance reading of 0.160. To the same sample we added 1.5ppm Fe and the new absorbance reading was 0.205. Calculate the ppm of the ...
*March 5, 2012 by Mae*

**Chemistry**

It is possible, although less accurate, to do a standard addition with only one sample. An unknown Fe sample was analyzed by AAS and gave an absorbance reading of 0.160. To the same sample we added 1.5ppm Fe and the new absorbance reading was 0.205. Calculate the ppm of the ...
*March 5, 2012 by Ella*

**Math**

A 30% solution of fertilizer is to be mixed with a 60% solution of fertilizer in order to get 150 gallons of 50% solution. How many gallons of the 30% and the 60% solutions should be mixed. I really need help.
*February 1, 2011 by Candice Watt*

**science(chem)**

[b]1.[/b]Is TLC a qualitative or quantitative analysis? Is there any way that it can be both? Explain. ~I say it can be both since it can be used to go and determine what exactly is in a sample of mixed compounds which would be qualitative analysis. It can also be quantitative...
*October 13, 2007 by ~christina~*

**Chem-Stoich**

A 1.605g sample of dry calcium carbonate and calcium chloride mixture was dissolved in 35.00mL of 1.000mol-dm-3 hydrochloric acid solution. The only portion of the mixture that reacts with the hydrochloric acid solution is the calcium carbonate. What was the calcium chloride ...
*January 7, 2015 by :)*

**STAT**

Given a sample size of 18, with sample mean 660.3 and sample standard deviation 95.9, we are to perform the following hypothesis testing: Null Hypothesis H0 : µ = 700 Research Hypothesis H1 : µ ≠ 700 •What is the test statistics? •At a 0.05 significance level, what is ...
*October 12, 2013 by Jacky*

**STAT**

Given a sample size of 18, with sample mean 660.3 and sample standard deviation 95.9, we are to perform the following hypothesis testing: Null Hypothesis H0 : µ = 700 Research Hypothesis H1 : µ ≠ 700 •What is the test statistics? •At a 0.05 significance level, what is ...
*October 13, 2013 by Jacky*

**chemistry**

A 33.8 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 20.7 g. What was the mass of iron in the sample of ore?
*August 30, 2012 by Nick*

**Chemistry**

one sample of magnesium fluoride produced 1.65kg of magnesium and 2.58kg of fluorine. A second sample produced 1.31kg of magnesium. How much fluorine (in grams) did the second sample produce?
*September 26, 2013 by Jay*

**chemistry help!**

Potassium has an atomic mass of 39.10amu. a sample of potassium is made up of isotopes potassium-39 (mass=38.964) and potassium-41(mass =40.962 amu). What percentage of the potassium sample is potassium-39? what percent of the sample is potassium-41?
*October 20, 2011 by Skylar*

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