Saturday
July 2, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
why hexane dissolved in toluene?
Saturday, February 20, 2016 by ben jackson

chemistry
The analysis of halogenated hydrocarbon gave the following results: A sample of mass m=255mg produces 273.7 mg carbon dioxide and 130.6 mg of water .A second sample of mass 87 is treated by hot molten sodium .The obtained mixture is dissolved in distilled water and filtered ....
Saturday, February 20, 2016 by vicky

Chemistry
a student found that the weight of the naphthalene collected was less than the weight determined by difference. what would account for the smaller amount of naphthalene collected?
Saturday, February 20, 2016 by Arif

Chemistry
How would you prepare a buffer (100ml) of pH 6.8 and concentration 0.1M given solid imidazole (mol wt.=68) and concentrated HCl
Saturday, February 20, 2016 by Tessie

Chemistry
which law of chemical combination is illustrated by the fact that 168 g of fe(iron) reacts with 72 g of water to form 232 g Fe3O4 and 8g H2
Saturday, February 20, 2016 by sajitha

AP Chemistry
Determine the pH of the following solutions. 1) 0.600 M HCl 2) 0.052 moles of H2SO4 dissolved in 4.2 L of water. 3)5.6 grams HNO3 dissolved in 450 ml of water. 4) 2.5 grams of NaOH dissolved in 500 mL of water. 5) adding 2 grams NaH dissolved in 0.56 L of water. 6) 20 mL of 0....
Saturday, February 20, 2016 by Tyra

AP Chemistry
Determine the pH of the following solutions. 1) 0.600 M HCl 2) 0.052 moles of H2SO4 dissolved in 4.2 L of water. 3)5.6 grams HNO3 dissolved in 450 ml of water. 4) 2.5 grams of NaOH dissolved in 500 mL of water. 5) adding 2 grams NaH dissolved in 0.56 L of water. 6) 20 mL of 0....
Friday, February 19, 2016 by Tyra

Chemistry
Gasoline, which can be represented by the formula octane, bulk density is 704 g / l. To estimate the variation in enthalpy when burning 28.5 liters gasoline, based on the binding energies: 0 = 0 (117 kcal); C = 0 (173 kcal); 0 h (111 kcal); C-C (83 kcal); C-H (99 kcal).
Friday, February 19, 2016 by Anonymous

Chemistry
1. Would it be advisable to determine the freezing point of pure p-dichlorobenzene with one thermometer and the freezing point of the solution with a different one? Explain. 2. If 0.150 mole of a nonvolatile non-electrolyte solute is present in 1200g of water, what are the ...
Friday, February 19, 2016 by Allie

Chemistry
what volume of 0.120 M NaOH must be added to 100 ml of 0.100 M NaHC2O4 to reach ph of 4.70? H2C2O4 Ka1 = 5.9 x 10-2 HC2O4^- Ka2 = 5.1 x 10-5 The answer is 60 ml but I dont know how to find it. Can you please show me the steps and how to do it please
Friday, February 19, 2016 by Steve

Chemistry-Dr.Bob 222
1. The rate constant for a second order reaction has units of L mol^-1 s^-1. What are the units of the frequency factor, A, for a second order reaction?
Friday, February 19, 2016 by Student

Chemistry
What is the required volume in ml to prepare a liter of solution 0.1 mol of nitric acid. molar mass 63 g / mol Density 1.41 g / ml, 75% weight by weight...
Friday, February 19, 2016 by Anonymous

chemistry!
what observations are made when you bubble chlorine into a solution of potassium iodide?
Friday, February 19, 2016 by laura

CHEMISTRY HELP
Calculate the amount (in mL) of 1.520M NaOH that is required to add the following acetic acid solution to prepare a buffer with the corresponding pH: 30.00mL of a 5.00% (w/v%) acetic acid; the resulting acetate buffer has a pH of 5.75. pKa of acetic acid = 4.74 So I got this: ...
Friday, February 19, 2016 by Mike

chemistry
An 11.1-g sample of CaCl2 is dissolved in 123 g water, with both substances at 24.0°C. Calculate the final temperature of the solution assuming no heat loss to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/°C·g.
Friday, February 19, 2016 by Zelzin

Chemistry
Using the equation: 2C2H6 + 7O2--> 4CO2 + 6H20 How many moles of CO2 are produced by the reaction of 21.0 mol O2? Again, not sure how to write it correctly, but if I multiply 7O2 by 3, then I should do the same to the other side of the equation to make it 12CO2?
Friday, February 19, 2016 by Eric

chemistry
Calculate RAM of Cu and S from the percentage abundances of their isotopes Use your answers to find the RFM of Copper (II) Sulfide, Cus 63Cu- 69.1% 65Cu - 30.9% 32 Sulphur-95.0% 33 S-0.76% 34S-4.22% 35S-0.20%
Friday, February 19, 2016 by vidya

Chemistry
Using the equation: 2C2H6 + 7O2--> 4CO2 + 6H20 How may moles of 02 are needed to react with 4.0 mol of C2H6? I think the answer is 14, because if you double the C2H6 to make 4.0 mol, then in the equation you will need to double the O2 to 14. Is this correct?
Thursday, February 18, 2016 by Eric

Chemistry
Calculate the molal concentration. A 1% (w/w) solution of cocaine hydrochloride ( molar mass 339.81 g/mol) in water.
Thursday, February 18, 2016 by Student

CHEMISTRY PLEASE HELP APPRECIATE IT LOTS!
7.) How many moles of fluroine are required to react with 12 g of sodium iodide? I already balanced it but am confused to go from here F2 + 2 NAi ---- 2 NaF + I2 12 g NaI + 2 mol NAI/149.89 gNAi * 1 mol NAF/1 mol NAi * 1 mol F2 / 2 mol NaF 1.) how many grams of magnesium are ...
Thursday, February 18, 2016 by Anon

chemistry
A gas sample contained in a cylinder equipped with a moveable piston occupied 300.0 mL at a pressure of 2.00 atm. What would be the final pressure if the volume were increased to 500.0 mL at constant temperature? Answer should include units.
Thursday, February 18, 2016 by Kyra

Chemistry
An atmospheric scientist interested in how NO is converted into NO2 in urban atmospheres carries out two experiments to measure the rate of this reaction. The data are tabulated below. A: [NO]0 = 9.63 × 10-1 M, [O2]0 = 4.1 × 10-4 M t(s) 0/3.0/6.0/9.0/12.0 [O2] 4.1/...
Thursday, February 18, 2016 by Jesse

chemistry
calculate the valume of 200g og h2
Thursday, February 18, 2016 by monayem

Chemistry
what volume of 0.120 M NaOH must be added to 100 ml of 0.100 M NaHC2O4 to reach ph of 4.70? The answer is 60 ml but I dont know how to find it. Can you please show me the steps and how to do it please
Thursday, February 18, 2016 by Steve

Chemistry
Calculate solubility of AgCl (in g/L) in a 6.5*10^-3 M silver Nitrate solution ksp= 1.8 * 10^-10 (AgCl molecular mass is 143.3g) any idea on how to do this this is what i tried> AgCl--> Ag + Cl I 6.5*10^-3 0 C same x E same x ksp = [Ag][Cl] (1.8 * 10^-10) = (6.5 * 10^-3)...
Thursday, February 18, 2016 by Steve

Chemistry
Five grams of sodium are combined with unlimited bromine. How many moles of bromine are used up? How many liters of bromine would be used if the reaction took place at STP? My answer: .1088 mole Br2 and 2.44 L Br2
Thursday, February 18, 2016 by Anonymous

Chemistry
Calculate solubility of AgCl (in g/L) in a 6.5*10^-3 M silver Nitrate solution ksp= 1.8 * 10^-10 (AgCl molecular mass is 143.3g) any idea on how to do this this is what i tried> AgCl--> Ag + Cl I 6.5*10^-3 0 C same x E same x ksp = [Ag][Cl] (1.8 * 10^-10) = (6.5 * 10^-3)...
Thursday, February 18, 2016 by Steve

chemistry
If 15.22 g of mercury (II) oxide decompose, how many moles of oxygen can be produced?
Thursday, February 18, 2016 by jules

Chemistry
How many mL of 1.2 M HCl is needed to react with 5.8 g of Al(OH)3
Thursday, February 18, 2016 by Chris

Chemistry
how do i figure out "What is the energy of 1 mole of these photons" energy= 2.93x10^-19 wave length = 670.8 nm
Thursday, February 18, 2016 by Manny

CHEMISTRY
Calculate the amount (in mL) of 1.520M NaOH that is required to add the following acetic acid solution to prepare a buffer with the corresponding pH: 30.00mL of a 5.00% (w/v%) acetic acid; the resulting acetate buffer has a pH of 5.75. pKa of acetic acid = 4.74
Thursday, February 18, 2016 by Jeff

Chemistry
the atomic spectrum of lithium has a strong red line at 670.8 nm. what is the energy of each photon of this wave length? What is the energy of 1 mole of these photons?? -do you use the e=h x v ??
Thursday, February 18, 2016 by Cali

Chemistry
16. Aluminum chloride, AlCl 3, is made by treating scrap aluminum with chlorine. 2 Al(s) + 3 Cl2(g) → 2 AlCl 3(s) If you begin with 2.70 g of Al and 4.05 g of Cl2, (a) Which reactant is limiting?
Thursday, February 18, 2016 by Marine.t

Chemistry
I NEED HELP ASAP Here's the problem I'm struggling with: When 1.00 mole of ethlyene (C2H4) is burned at constant pressure, 1410 kJ of energy is released as heat. Calculate delta H for a process in which 10.0 g of ethlyene is burned at constant pressure. Please show me ...
Thursday, February 18, 2016 by Ian

Chemistry
Five grams of sodium are combined with unlimited bromine. How many moles of bromine are used up? How many liters of bromine would be used if the reaction took place at STP? My answer: .1088 mole Br2 and 2.44 L Br2
Thursday, February 18, 2016 by Anonymous

Chemistry
the atomic spectrum of lithium has a strong red line at 670.8 nm. what is the energy of each photon of this wave length? What is the energy of 1 mole of these photons??
Thursday, February 18, 2016 by Maxx

Chemistry
1) If I add 10 grams of salt into 0.1 L of water, what is the molarity of the solution? 2) Serial dilution is a common technique to make low concentration solutions. Each Serial Dilution involves taking half the solution and mixing it with a solvent, to halve the concentration...
Thursday, February 18, 2016 by Caitlyn

Chemistry 101
what is CAH2 + H20
Thursday, February 18, 2016 by Linda

chemistry
why does phosphorous and some other elements have two or more oxidation states
Thursday, February 18, 2016 by vidya

chemistry
Hcl is titrated against 5ml of sodium carbonate of strength 0.0133 then what should be the mean value of HCl added ?
Thursday, February 18, 2016 by Shareen

chemistry
a student was investigating the properties of a liquid L. He found that it turned phenolphthalein indicator red but when a piece of litmus paper was dipped into liquid L it turned blue. Which of these liquids could it be? a Aqueous ammonia b Lemon juice c copper sulphate ...
Thursday, February 18, 2016 by vidya

chemistry
based on your calculated rf values which cations formed weakly charged complexes
Thursday, February 18, 2016 by jawaher

chemistry
chlorine atoms have larger radii than fluorine A. True B. false I am unsure Answer Th
Wednesday, February 17, 2016 by sharon

CHEMISTRY!!!! HELP
3.) Calculate the mass of oxygen gas that can be produced in the decomposition of 5.55 g of silver oxide. This is what I did but is it right?... I need help with a few more btw to double check if i'm doing these right. So here is what I did: First: balance the equation 2 ...
Wednesday, February 17, 2016 by Sam

chemistry
Calculate the energy (in kJ) required to heat 25 g of liquid water from 25oC to 100.oC and change it to steam at 100oC. The specific heat capacity of liquid water is 4.18 J/goC, and the molar heat of vaporization of water is 40.6 kJ/mol.
Wednesday, February 17, 2016 by maria

science, chemistry
Calculate the final Volume of solution obtained if 100.0 mL of 12.0 M NaOH is diluted to 5.20M
Wednesday, February 17, 2016 by Amy

Chemistry
1.) what mass of zinc is needed to completely react with 4.00 g of silver nitrate? 2.) If excess ammonium sulfate reacts with 22.5 g of calcium hydroxide according to the following unbalanced chemical equation: (NH4)2 SO4 + Ca (OH)2 → CaSO4 + NH3 + H2O Now, how do I go ...
Wednesday, February 17, 2016 by Sam

Chemistry Help please! (:
Calculate the mass of oxygen gas that can be produced in the decomposition of 5.55 g of silver oxide. This is what I did but is it right?... I need help with a few more btw to double check if i'm doing these right. So here is what I did: First: balance the equation 2 Ag2 O...
Wednesday, February 17, 2016 by Sam

Chemistry
Please,tell me the ways I can use to understand chemistry better.I need help,and it is urgent because am starting to drop.
Wednesday, February 17, 2016 by Miracle

Chemistry
How many grams of salt can be produced from five grams of sodium and unlimited bromine? Is this 39.75 g NaBr?
Wednesday, February 17, 2016 by Anonymous

Chemistry
Okay so I understand this is incredibly unconventional, but I have a big favor to ask. I just got a chem exam back and my teacher still has not posted my scantron score. I was wondering if it is at all possible for you guys to just spot-check for accuracy. It can be rough or ...
Wednesday, February 17, 2016 by Justin

chemistry
What is the bond of a salt molecule? A. covalent B. hydrogen C. disulfide D. ionic I think A
Wednesday, February 17, 2016 by sharon

chemistry
S and O share chemical properties, but H2S is gas at room temp. and H2O is a liquid, why? A. H2O has stronger intermolecular bond B. H2S has a stronger intermolecular bond C. H2S has a stronger ionic bond D. H2O has a stronger ionic bond
Wednesday, February 17, 2016 by sharon

chemistry
The hands on a battery clock are which type of energy? A. chemical to kinetic B. potential to chemical C. kinetic to potential D. thermal to kinetic I think C
Wednesday, February 17, 2016 by sharon

chemistry
what is the percentage yield of c2h2 with 50g of cac2 reacts with water to yield 13.5g of c2h2
Wednesday, February 17, 2016 by francis

Chemistry
On a clear day at sea level, the partial pressure of N2 in air is 0.78 atm at 25 degres C. Under these conditions, the concentration of N2 in water is 5.3 x 10^-4 M. What is the partial pressure of N2 when the concentration in water is 3.5 x10^-4 M?
Wednesday, February 17, 2016 by Student

Chemistry
A solution is 0.10M in aqueous NH3. Calculate (a) the number of moles and (b) the number of grams of NH4Cl that must be added to 500mL of this solution to prepare a buffer solution with pH=9.15. You may neglect the volume change due to addition of solid NH4Cl. Kb=1.8x10^-5. (...
Wednesday, February 17, 2016 by Chen

Chemistry
I've worked through this problem so many times and I keep getting the same thing yet when I submit it, it says its wrong.. Am I missing something? Q:Calcium hydride (solid) reacts with water to form calcium hydroxide (aqueous) and hydrogen gas. Write a balanced chemical ...
Tuesday, February 16, 2016 by Chem: Troubleshooting

Chemistry
NaCl + H2O + CO2 + NH3 ______> NaHCO3 + NH4Cl 1) You dissolve an excess of NaCl in a solution containing 50.0 mL of 4.77 M ammonia. You bubble in an excess of CO2. Calulate the theoretical yield of sodium bicarbonate. I have no idea how to do this, can I know the step by ...
Tuesday, February 16, 2016 by eylow

chemistry
what does the spectrum of hydrogen tell us about its electrons?
Tuesday, February 16, 2016 by Mia

chemistry
why are there only certain colours in an atomic emission spectra?
Tuesday, February 16, 2016 by Emily

chemistry
assuming in the titration of NaCl and AgNO3, a student erroneously carried it out at a low PH,what effect will it be on the result. explain with an ionic equation
Tuesday, February 16, 2016 by Mina

chemistry
a piece of chalkboard dissolvedin acid solution and the solution bubbled vigorously.The gas caused barium hydroxide solution to form a white precipitate.what is the gas given off?what is the white precipitate?write a chemical equation for the formationof the white precipitate.
Tuesday, February 16, 2016 by semisi caucau

chemistry
what is thiosulphate
Tuesday, February 16, 2016 by Timmy

Chemistry
why is chemistry needed
Tuesday, February 16, 2016 by Timmy

Chemistry: stoich
4. Suppose that an excess of propane, C3H8 , burns in 320 g of oxygen, How many moles of water will be formed? C3H8 + 5 O2 --> 3 CO2 + 4 H2O (1 point) 6.02 E 23 moles 1600 moles 4.0 moles 8.0 moles
Tuesday, February 16, 2016 by Hannah

Chemistry
5. How many grams of iron oxide can be produced from 2.50 g of oxygen reacting with iron, according to the following equation? 2 Fe (s) + 3 O2 (g) -->2 Fe2O3(s)
Tuesday, February 16, 2016 by Hannah

Chemistry
5. How many grams of iron oxide can be produced from 2.50 g of oxygen reacting with iron, according to the following equation? 2 Fe (s) + 3 O2 (g) -->2 Fe2O3(s)
Tuesday, February 16, 2016 by Hannah

Chemistry
Describe how you would distinguish between solutions NH4Cl and NaCl using litmus paper
Tuesday, February 16, 2016 by Miracle

Chemistry
how to separate a mixture of iron filings, salt, sand and wood chips.
Tuesday, February 16, 2016 by Jojo

chemistry
A sample of NH4HS(s) is placed in a 2.57 −L flask containing 0.140 mol NH3(g). NH4HS(s)⇌NH3(g)+H2S(g)KP=0.108at25​∘C What will be the total gas pressure when equilibrium is established at 25∘C? any idea on how to solve it like an outline? Thanks
Tuesday, February 16, 2016 by Steve

Chemistry
I have been stuck on this question please help me solve it? The following reaction is used in some self-contained breathing devices as a source of O2(g). 4KO2(s)+2CO2(g)⇌2K2CO3(s)+3O2(g)Kp​=28.5at25∘C Suppose that a sample of CO2(g) is added to an evacuated ...
Tuesday, February 16, 2016 by Steve

Chemistry
How do I determine the value of the reaction 2HI(g) + 2.4 kcal --> H2(g) + i2(g) delta H = a) 2.4 kcal b) -2.4 kcal c) 0.00024 kcal d) -0.00024 kcal
Tuesday, February 16, 2016 by Susan

Chemistry
How do I determine the value of the reaction 2HI(g) + 2.4 kcal --> H2(g) + i2(g) delta H = a) 2.4 kcal b) -2.4 kcal c) 0.00024 kcal d) -0.00024 kcal
Tuesday, February 16, 2016 by Susan

Chemistry, chemical change
N2(g) + 3H2(g) --> 2NH3(g)+ 22,000. ^H = a) 22,000 kcal b)-22,000 kcal c)22 kcal b)-22 kcal
Tuesday, February 16, 2016 by Alana

Chemistry
Assuming ideal behavior, determine the mole fraction of acetone in a solution of acetone and water if the vapor pressure of acetone changed from 750mmHg to 735mmHg.
Monday, February 15, 2016 by Karla

Chemistry
Determine the vapor pressure (in atm) of water in an aqueous solution of 12% by mass ethylene group (antifreeze) if the vapor pressure of pure water at that temperature is 0.095 atmospheres.
Monday, February 15, 2016 by Samantha

Chemistry
A 10.0 L container contains 1.0 L of solution of a gas. Assume [gas]=1.5x10^-4 M in solution when 2 mol of gas remain in gas form. If 1 mol of gas is removed from the gas phase, what will be the new concentration of the gas in solution? What is the value of k?
Monday, February 15, 2016 by Sarah

Chemistry
How many grams of salt can be made from a 5-gram sample of sodium combined with unlimited bromine?
Monday, February 15, 2016 by Anonymous

Science
I'm really bad at Biology and Science in general. Chemistry and Physics will be difficult for me because I'm not good at the Science branch even though I study and work hard for Science/Biology. What can I do to improve?
Monday, February 15, 2016 by Anonymous

chemistry
Iron can be produced by the reduction of iron(III) Oxide by carbon monoxide: Fe2O3 + 3CO -> 2FE +3CO2 a) what maximum mass of CO2 could be produced from the complete reduction of 14.7g of Fe2O3? b) if 8.73g of CO2 gas was actually collected, what percentage yield of the ...
Monday, February 15, 2016 by Emily

chemistry
when 130.4 mL of 0.459 mol/L silver nitrate solution is mixed with 85.23mL of 0.251 mol/L aluminum chloride solution, a precipitate of silver chloride forms. Find the mass of this Precipitate.
Monday, February 15, 2016 by Emma

Chemistry
A 4.00g piece of magnesium is added to 200mL of 1.40 mol/l HC. Identify the limiting reactant, and calculate the mass of hydrogen gas that should be produced
Monday, February 15, 2016 by Jeddediah

chemistry
a solution containing 13.75g of barium hydroxide is to be neutralized with a 0.150 mol/L phosphoric acid solution. what volume of the acid solution will be required?
Monday, February 15, 2016 by Maxine

chemistry
potassium chlorate can be thermally decomposed to oxygen and potassium chloride. calculate the mass of potassium chlorate that must be decomposed by heat to produce 10.0L of oxygen gas at 150 degrees celsius and 150 kPa pressure
Monday, February 15, 2016 by Max

chemistry
what volume of hydrogen gas, measured at STP, will be produced when 16.0g of magnesium reacts completely with an excess of hydrochloric acid
Monday, February 15, 2016 by Mia

Chemistry 1
i need help as quickly as possible because i am taking a summative practice test and this question i don't understand how to work it out. can you please explain? here is the question: Arrange the following in order of increasing oxidation number of the sulfur atoms in ...
Monday, February 15, 2016 by Elizabeth

Chemistry
Can you determine the limiting reactant just by comparing the masses of the reactants in a reaction?
Monday, February 15, 2016 by Anonymous

Chemistry
estimate the heat of vaporization of water if the vapor pressure is 17.54 torr at 20C and 149.4 torr at 60C. R=8.314 J/mole K. I can't remember how to set up the problem. Would someone be able to send me the formula? Thank you
Monday, February 15, 2016 by Emma

Chemistry
Hey there! I have these two questions for my chemistry class, and I am a little confused on how I should go about solving them. If someone could give me the steps necessary to solve these problems I would be most appreciative. 1.) p-Toluenesulfinic acid undergoes a second-...
Sunday, February 14, 2016 by Ka_Chin

Chemistry
Create a balanced equation for the reaction between sodium and bromine. Find how many grams of salt can be made from 5.00 grams of sodium and unlimited bromine. Is it about 39.8 g NaBr2?
Sunday, February 14, 2016 by Anonymous

Chemistry
At what pressure would 0.150 mole of nitrogen gas at -23.0^o C occupy 8.90 L ?
Sunday, February 14, 2016 by Boberto

Chemistry
What Mass Of Copper(i)oxide Is Formed By Burning 10.5g Of Copper(i)sulfide
Sunday, February 14, 2016 by Precious

Chemistry
What is the volume of 2.0 kg of isopropyl alcohol at 20 degrees Celsius? Density at 20 degrees is 0.785g/ml. I got .00255 ml when using 3 sig figs.
Sunday, February 14, 2016 by Kaylee

chemistry
If a solution containing 22.34 g of mercury(II) perchlorate is allowed to react completely with a solution containing 6.256 g of sodium sulfate, how many grams of solid precipitate will be formed?
Sunday, February 14, 2016 by alex

Chemistry
This is a stoichiometry equation. Cu(s) + 4(HNO3)(aq) -> Cu(NO3)2(aq) + 2(NO2)(g)+2(H2O)(l) If you use 6 moles of nitric acid 4(HNO3), how many moles of Copper (II) Nitrate Cu(No3)2 will be produced?
Sunday, February 14, 2016 by Bryce

Chemistry
A solution containing equal masses of glycerol, C3H8O3, and water has a density of 1.10 g/mL. Calculate the molality of glycerol. I got 11.9 m.
Sunday, February 14, 2016 by Student

Chemistry
A first-order reaction has a half-life of 26.4 seconds. How long does it take for the concentration of the reactant in the reaction to fall to one-eighth of its initial value?
Sunday, February 14, 2016 by Student

chemistry
Consider a sample of excited atoms that lie 3.211 × 10–19 J above the ground state. Determine the emission wavelength (in nanometers) of these atoms.
Sunday, February 14, 2016 by Anisha

chemistry
The first ionization energy, E, of a boron atom is 1.33 aJ. What is the wavelength of light, in nm, that is just sufficient to ionize a boron atom? Values for constants can be found here.
Sunday, February 14, 2016 by Bibi

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Homework Help: Science