Friday

April 25, 2014

April 25, 2014

Total # Posts: 165

**3rd grade math**

1 Whole pizza

**algebra**

is 10/11 rational or irrational ?

**Math**

Thank you so much this is better than the way my teacher explained. :)

**Math**

Jeremy got scores of 93,82,91, and 88 on his first four math test. What score must he get on the fifth test to have an average test grade of 90 for the five test ? Can someone explain step by step. Please

**math **

what is the answer to x-3=-1

**physical sciences**

The density of mercury is 13.54 g/cm3. Suppose you need 40 gm of mercury for an experiment. What volume of mercury do you need?

**general chemistry **

The gas with a pressure of 1100 at 175 is cooled to 0 °C find out what the Pf= in torr

**Physics**

A 6.7 kg package starts from rest and slides down a mail chute that is 50 m long and has a vertical drop of 10m. If the velocity of the package at the bottom of the chute is 4m/s what is the average frictional force on the package as i slides down the chute?

**Physics**

a 0.2kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30 m/s and rebounds up at 25 m/s. If the ball is in contact with the sidewalk for 0.025s, what is the magnitude of the average force applied by the sidewalk on the ball?

**physics**

The mass is not given in the problem, does that mean it cancels out?

**physics**

a skier moving at 15 m/s down a 20 degree slope encounters a region of wet snow of coefficient of friction is 0.8. how far down the slope does she go before stopping

**Physics **

a 0.2kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30 m/s and rebounds up at 25 m/s. If the ball is in contact with the sidewalk for 0.025s, what is the magnitude of the average force applied by the sidewalk on the ball? I need steps...

**Math**

Thank you

**Math**

Kayla is 5 feet tall, and Maria is 5.5 feet tall. Kayla's shadow at 3pm outdoors measured 3feet. The length of each persons shadow is proportionate to her height. How many feet long is Maria's shadow at 3pm.

**math models**

Tanisha wants to have $1000 in her bank account in 5 years. How much money should she deposit if her account earns 6% interest which is compounded 2 times per year?

**Math**

Israel has 72 apples.12of them are red .What percentage of the apples are red

**Math**

What place value is ten times smaller than ten millions place? A) hundred trillion B) one trillion C) hundred billion D) ten billion I think it's ones place. But that's not an option, maybe they did a typo.

**math**

Dominoes pizza offers 30 different types of pizza and 9 of them contain pepperoni. what percentage of their total number of pizza types have pepperoni on it? Can someone explain to me the procedure please

**math**

determine the value of N: N/20 * 100%=60% can someone explain

**us history **

what does a full-fledged American mean?

**Algebra**

4+2z what is the value of the constants in this expression? Can anyone help

**math**

THANK YOU

**math**

ramos was falling through the air of 30feet per second. how many feet did ramos fall in the 110 seconds before she opened her parachute?

**Math**

THANK YOU

**Chemistry **

IF 80mg of a radioactive element decays to 10mg in 30 minutes, the half-life of this element is a.10 min b.20 min c.30 min d.40 min the answer is a.10 min but i would like to know why, please help.

**Chemistry **

which of the following 10 g samples will decay the most in 28 days? a.P-32 b.Kr-85 c.Fr-220 I-131 the answer is c.Fr-220 but i want to know why, please help

**chemistry **

A unknown piece of metal is placed into a container of acid. Hydrogen gas was produced as a result. The unknown metal could have been ? Ti is the answer, but I don't understand why.

**chemistry **

which of the following 10 g samples will decay the most in 28 days? P-32 Kr-85 Fr-220 I-131

**Pre-calculus**

Turn "theta = 2" into rectangular form.

**Chemistry**

K-42 has a half-life of 12.4 hours. If you begin with 250g of K-42, determine how much you will have left after 4 half-lives. How long does 4 half-lives take? please help

**chem**

radiated food can be safely stored for a longer time because radiation 1. prevents air oxidation 2. prevents air reduction 3. kills bacteria 4. causes bacteria to mutate is it 3 ?

**Chemistry**

which isotope can be used as a tracer to study the age of organic material ? 1 C-12 2 C-14 3 Tc-99 4 U-238

**Chemistry**

a radioisotope is called a tracer when it is used to 1 kill bacteria 2 kill cancerous cells determine the age of animal skeletal remains 4 determine the path of an element in an organism is it 3 ?

**Chemistry**

which process occurs in a controlled fusion reaction? 1 light nuclei collide to produce heavier nuclei. 2 heavy nuclei collide to produce lighter nuclei. 3 neutron bombardment splits light nuclei 4 neutron bombardment splits heavy nuclei. is it 1 ?

**Chemistry**

which process occurs in a controlled fusion reaction? 1 light nuclei collide to produce heavier nuclei. 2 heavy nuclei collide to produce lighter nuclei. 3 neutron bombardment splits light nuclei 4 neutron bombardment splits heavy nuclei. is it 1 ?

**Chemistry**

compared to an ordinary chemical reaction, a fission reaction will 1 release smaller amounts of energy 2 release larger amounts of energy 3 absorb smaller amounts of energy 4 absorb larger amounts of energy is it 2 ?

**Chemistry**

what is the primary result of a fisson reaction ? 1 conversion of mass to energy 2 conversion of energy to mass 3 binding together of two heavy nuclei 4 binding together of two heavy nuclei i think its 4, am i right ?

**algebra**

Last month, your electric bill was $25.32 for 450 kilowatt-hours of electricity. At that rate, what would be the bill for 240 kilowatt-hours?

**College Algebra**

I do not know how to rationalize this: 2(-2/radical 77)(77/73)......the answer is -4 radical 77/73 Thank you!!!

**math 4th grade**

how do you writ $1,044 in word form.

**math**

2/3-5/12+4/9 simplify

**chemistry**

Azomethane, CH3NNCH3, is not a stable compound, and once generated, it decomposes. The rate of decomposition was measured by monitoring the partial pressure of azomethane, in torr. Time (min) 0, 15, 30, 48, 75 Pressure(torr)36.2, 30, 24.9,19.3, 13.1 Determine the instantaneous...

**chemistry**

Write a balanced chemical equation for the overall cell reaction represented as: a) Ag(s)|Ag^+(aq)||Sn^4+(aq), Sn^2+(aq)|Pt(s) b) Al(s)|Al^3+(aq)||Cu^2+(aq)|Cu(s) c) Pt(s)|Fe^2+(aq), Fe^3+(aq)||MnO4^-(aq),Mn^2+(aq)|Pt(s)

**chemistry**

Write a balanced chemical equation for the overall cell reaction represented as: a) Ag(s)|Ag^+(aq)||Sn^4+(aq), Sn^2+(aq)|Pt(s) b) Al(s)|Al^3+(aq)||Cu^2+(aq)|Cu(s) c) Pt(s)|Fe^2+(aq), Fe^3+(aq)||MnO4^-(aq),Mn^2+(aq)|Pt(s)

**Environmental engineering**

The company you work for plans to release a waste stream containing 7 mg/L of benzaldehyde . Assuming that benzaldehyde degrades according to the reaction: C7H6O + 8O2 → 7CO2 + 3H2O Calculate the theoretical carbonaceous oxygen demand of this waste stream in mg/L.

**chemistry**

The pH of a 0.10 M solution of ammonia is 11.1. Find the hydroxide concentration.

**pre-algebra **

Graph the equation. Tell whether the equation is a function. y = -x

**writing**

Thank you so much

**writing**

what about I just heard the news and it made me happy. i think HEARD would be the adjective or it could also be HAPPY

**writing**

which is the adjective in the sentence. Our house is built from wood. can any help, by the way if theres no adjective its fine but i want ot make sure if there is or not

**Chemistry**

Assume equal aqueous concentrations of each of the following substances. Which has the lowest freezing point? C2H12O6 CH3OH C12H22O11 NaOH i say its NaOH am i right ?

**chemistry**

(10 Points) A water initially contains 50 mg/L of Mg 2+ The pH of the water is increased . until the concentration of hydroxide ion is 0.0005 M. Calculate the concentration (mg/L) of magnesium ion in this water at this pH. Assume that the temperature of the solution is 25˚C

**Environmental engineering**

(10 Points) A contractor is trying to estimate the distance to be expected of a drawdown of 4.81 m from a pumping well under the following conditions: Pumping rate = 0.0280 cubic meter per seconds Pumping time = 1066 d Drawdown in observation well = 9.52 m Observation well is...

**Environmental engineering**

Thanks, I wasn't converting to cubic meters. Now I got it!!!!!!

**Environmental engineering**

Lake Kickapoo, TX, is approximately 12 km in length by 2.5 km in width. The inflow for the month of April is 3.26 cubic meter per second, and the outflow is 2.93 cubic meter per second. The total monthly precipitation is 15.2 cm and the evaporation is 10.2 cm. The seepage is ...

**chemistry**

The solubility of NaCl in water is 35.7g NaCl/100g H2O. Suppose that you have 500.0g of NaCl. What is the minimum volume of water you would need to dissolve it all? (Assume that de density of water is 1.0 g/mL.)

**chemistry**

The solubility of NaCl in water is 35.7g NaCl/100g H2O. Suppose that you have 500.0g of NaCl. What is the minimum volume of water you would need to dissolve it all? (Assume that de density of water is 1.0 g/mL.)

**Environmental science**

Estimate the chronic daily intake of 1,1,1-trichloroethane from exposure to city water supply that contains a 1,1,1-trichloroethane concentration equal to the drinking water standard of 0.2 mg/L. Assume the exposed individual is a child who consumes water at the child rate for...

**chemistry**

Thanks!!!!!

**chemistry**

If 14.8 kJ of heat is given off when 1.6 g of HCl condesses from vapor to liquid, what is the delta Hcond. for this substance?

**engineering**

Thanks so much, I was confused and then I used specific gravity formula and i got 167 lb.

**engineering**

100 lb of loose gravel can fill a 1-ft^3 box. Its specific gravity is 2.68. What is the dry rodded weight?

**chemistry**

Thanks So Much!!

**chemistry**

Another “grand challenge” for engineering is managing the nitrogen cycle. Use the nature of the chemical bond in diatomic nitrogen to explain why any management is needed for this biogeochemical cycle. With so much nitrogen available in the atmosphere, why are engine...

**chemistry**

If boron hydride, B4H10, is treated with pure oxygen, it burns to give B2O3 and H2O. 2 B4H10(s) + 11 O2(g) 4 B2O3(s) + 10 H2O(g) If a 0.050-g sample of the boron hydride burns completely in O2, what will be the pressure of the gaseous water in a 4.25-L flask at 30. &d...

**science**

Each month the Speedy Dry Cleaning Company buys one barrel (0.160 m3) of dry cleaning fluid. Ninety percent of the fluid is lost to the atmosphere and 10% remains as residue to be disposed of. The density of the dry cleaning fluid is 1.5940 g/mL. Draw a mass-balance diagram a...

**Environmental science**

Each month the Speedy Dry Cleaning Company buys one barrel (0.160 m3) of dry cleaning fluid. Ninety percent of the fluid is lost to the atmosphere and 10% remains as residue to be disposed of. The density of the dry cleaning fluid is 1.5940 g/mL. Draw a mass-balance diagram an...

**Environmental science**

A municipal landfill has available space of 16.2 ha at an average depth of 10 m. Seven hundred sixty-five (765) m3 of solid waste is dumped at the site 5 days a week. The waste is compacted to twice its delivered density. Draw a mass-balance diagram and estimate the expected l...

**physics**

The anchor shackle supports a cable force of 600 lb. If the pin has a diameter of 0.25 in., determine the average shear stress in the pin.

**chemistry**

A chemical is placed in a beaker containing 20 g of soil and 500 mL of water. At equilibrium, the chemical is found in the soil at a concentration of 100 mg/kg of soil. The equilibrium concentration of this same chemical in the water is 250 µg/L. Calculate the partition ...

**chemistry**

Convert the concentration of SO2 from 80µg/m^3 to units of parts per million. The gas has temperature of 25 degree Celsius and a pressure of 101.325 kPa.

**chemistry**

One liter of a gas mixture at 0 degree Celsius and 108.26 kPa contains 250 mg/L of H2S gas. Calculate the partial pressure exerted by gas.

**chemistry**

Calculate the "exact" alkalinity of a water that contains 0.6580 mg/L of bicarbonate, as the ion, at a pH of 5.66.

**chemistry**

Groundwater in Pherric, New Mexico, initially contains 1.800 mg/L of iron as Fe3+. What must the pH be raised to in order to precipitate all but 0.3 mg/L of the iron? The temperature of the solution is 25 degree Celsius.

**chemistry**

I don't understand step 3?

**chemistry**

Copper reacts with sulfuric acid according to the following equation: 2H3SO4 + Cu-> CuSO4 + 2H2O + SO2 How many grams of sulfur dioxide are created by this reaction if 14.2 g of copper reacts with 18 g of sulfuric acid?

**chemistry**

Ammonia gas can be prepared by the reaction CaO(s) + 2NH4Cl(s) -> 2NH3(g) + H2O(g) + CaCl2(s) If 112 g CaO reacts with 224 g NH4Cl, how many moles of reactants and products are there when the reaction is complete?

**chemistry**

Ammonia gas can be prepared by the reaction CaO(s) + 2NH4Cl(s) -> 2NH3(g) + H2O(g) + CaCl2(s) If 112 g CaO reacts with 224 g NH4Cl, how many moles of reactants and products are there when the reaction is complete?

**Math**

What is the next number in the pattern 20000 4000 800 160

**Math**

What is the next number in the pattern 20000 4000 800 160

**algebra **

How do you get : x=1/3y+2 in the y=mxtb form ?

**Chemistry**

thanks :) so its (3) right ?

**Chemistry**

the difference between the boiling point and the freezing point of pure water at standard pressure is (1)32 K (2)273 K (3)100 K (4)373 K

**Chemistry**

the difference between the boiling point and the freezing point of pure water at standard pressure is (1)32 K (2)273 K (3)100 K (4)373 K

**Chemistry**

which phase change is endothermic ? (1)gas-->solid (2)gas-->liquid (3)liquid-->solid (4)liquid-->gas

**Chemistry**

is it (2) ?

**Chemistry**

As a substance changes from liquid to gas, the average distance between molecules (1) decreases (2)increases (3) remains the same

**Chemistry**

which substance has a definite shape and a definite volume at STP ? (1)NaCl(aq) (2)Cl2(g) (3)CCl4(l) (4)AlCl3(s) is it 4 because its a solid? Am i right ?

**math**

how would i convert to decimal?

**math**

order the fractions from greates to least. 1/6, 2/7, 1/5. Can anyone help and explain this to me please

**Chemistry**

A covalent bond forms when (1)two nuclei share electrons in order to achieve a complete octet of electrons (2) atoms form ions and then electrostatic forces of attraction bond the ions together. (3)repulsive forces between atoms are greater than the attractive forces (4) a met...

**calculus**

differentiate: y = 2x/1 - 3x^2

**Chemistry**

Which atom has a larger atomic radius, Ca or Ra? Why?

**calculus**

thank you very much

**calculus**

find point(s) on the graph of the function f(x) = x^3 - 2 where the slope is 3

**question for DR.BOB**

Are you a retired teacher? Well it looks like you really like chemistry, since you are the one who answers most of the chemistry questions.

**question for DR.BOB**

Oh...do you like doing this? It doesn't seem fun

**question for DR.BOB**

Arizona

**question for DR.BOB**

oh thats cool...thats why you are 2 hours ahead from where im at thank you for responding

**question for DR.BOB**

where are you helping from? I'm just curious