# Posts by Laura

Total # Posts: 1,250

**science**

How does a hydrogen atom have so many spectral lines when it only has one electron? That one electron can occupy many, many different energy levels.

**science**

How do I use the fact that each element has a different set of energy levels to explain why the colour of the light emitted by an element in the gaseous state is characteristic of the element? Energy affects frequency and frequency determines wavelenght. The color of an ...

**chemistryI**

If 2 protons and 2 neutrons are ejected from a radium nucleus with atomic number 88 and mass number 226 which element will be the result? Could someone please tell me how to work this out. Thanks. The atomic number is the count of protons...so if two are ejected, the new ...

**science**

Re identifying forces, thankyou to Rom for your help, ive now been able to do most of them. One's i am still stuck on are a bungee jumper, speeding train, cyclist speeding off a ramp and a shuttlecock falling to the ground. bungee jumper: cord tension and gravity, air ...

**Science**

Im having trouble identifying forces. I have pictures of things like a man parachuting and a girl skating. I have to draw arrows to show the direction of the force and label to say the forces acting on each object. Parachuter has force of gravity pushing down while wind ...

**chem - Urgent, please help**

0.702g arsenic combines with 0.225g of oxygen to make an oxide of arsenic. When heated this produces a gas with a volume of 52cm3. How do i work out the molecular formula of the oxide when its in a gaseous state? The weight ratio will tell you, after dividing by atomic weights...

**chemistry**

How do I calculate the mas of oxygen that combines with one mol of arsenic atoms to form the oxide of arsenic? How would I use this answer to obtain the empirical formula of the oxide? The formula for the most common form of arsenic oxids is As2O3. Write down the balanced ...

**Chemistry**

If the percentage of arsenic is 76% and the percentage of oxygen is 24% how do I calculate the chemical composition of the oxide of the arsenic? Thanks Pretend you have 100 grams of the stuff. Then 76 grams of As is how many moles? 76/74.9 =1.01 moles. How many moles is 24 ...

**Chemistry**

If I have the temperature, the pressure and the mass how do I calculate the volume? Thanks Of a gas? PV=nRT The ideal gas law. calculate n from the mass and mol mass.

**chemistry - check please**

Have I balanced this right Al2Se3 + 6 H2O ==> 2 Al(OH)3 + 3 H2Se Let me give you a hint on these, write water as HOH, and it balances faster. Treat the OH as a group. Al2Se3 + 6 H(OH) ==> 2 Al(OH)3 + 3 H2Se Yes, it is balanced: see the six H on each side, and the six OH ...

**forces**

What forces can be seen in action in the classroom Gravity, for one. It's what keeps people in their seats. What about whatever moves the hands of the clock on the wall, or the chalk on the blackboard, or the door on its hinges?

**English**

Is this a strong thesis statement: Ms Gilman captures the struggle of the narrator as she provides evidence of the journey of the narrator’s changing mental state that is not just about a woman losing her sanity but of a woman who is suffering from a feeling of entrapment...

**math**

1 1/2 * 3 1/5 = 1 1/2 = 3/2 3 1/5 = 16/5 Multiply numerator and denominator to arrive at the answer. Be sure and reduce the fraction if possible. Please help Angelina!!!!!!!!!! With Math.

**calculus plz heLP**

can someone please prove the difference rule to me? d/dx[f(x)-g(x)]=d/dx f(x)- d/dx g(x) Go to the definition of a derivative: Lim x>0 of {f(x+deltax)-f(x)]/deltaX

**Calculus**

can someone please prove the difference rule to me? d/dx[f(x)-g(x)]=d/dx f(x)- d/dx g(x) plz help

**SPANISH**

proofread- thanks! revelado a Dali en un sueno. Esto tambien acentua que no era los clavos que sostenian a Cristo en la cruz, pero su amor para la gente. En esta picture, la brazo de Cristo forma un triangulo mientras su cabeza está en la forma de un círculo. ...

**Spanish**

proofread- thanks! revelado a Dali en un sueno. Esto tambien acentua que no era los clavos que sostenian a Cristo en la cruz, pero su amor para la gente.

**Economics**

I don't know

**math,algebra**

2x+28<6x -2x -2x 28<4x - - 4 4 7<x =x>7

**ethics**

Ok, so first I want to say that it is ETHNICS, not ethics... but yes I am also having difficulty with this one, just like the rest of you, but the thing is that it is a research paper, where you have to research the topic... research... meaning, search for info. The only thing...

**science - controlled experiment**

This doesn't seem like it should be that hard, but it is. List the 2 parts of a controlled experiment. _____ variable-- the factor that is not being tested (know expected outcome) _____ variable -- the factor that is being tested I feel like the answers should be dependent...

**Pigskin Geography**

someone plz help me

**Pigskin Geography**

i need the answers for week #5 of 08

**Pigskin Geography**

i need answers for week #3 of 08

**Pigskin Geography**

i need answers for week 3 of 08

**physics**

A heavy flywheel rotating on its central axis is slowing down because of friction on its bearings. At the end of the first minute of slowing, its rotational speed is 0.90 of its intial rotational speed of 250 rev/min. Assuming a constant rotational acceleration, find its ...

**Physics**

A wheel has a coonstant rotational acceleration of 3.0 rad/s^2. During a certain 4.0 s interval, it turns through an angle of 120 rad. Assuming that the wheel starts from rest, how long is it in motion at the start of the 4s interval. I just need help in getting started. I ...

**Physics**

Two objects, each with a charge of +3·10-6 C, are located 7 m apart. What is the electric force between them? Use coulombs equation: I will be happy to critique your work.

**Physics**

If travelling waves move at 140 m/s on this string, what musical note is this string currently producing? In hertz The fundamental is 1/2 wavelength. So you have to know string length. wavelength*fundamentalfreq= wave speed.

**macroeconomics**

State the four sections of a buisness cycle. state endogenous and exogenous conditions that affect the buisness cycle. Explain the reasons that inventories of producers are an impoertant in the growth-and decline-in a buisness cycle. Take a shot. Be sure to do a little ...

**Chemistry**

25.0 cm cubed of Barium hydroxide,Ba(OH)2 solution neautralises 35.0 cm cubed of aqueous hydrochloric acid of concentration 0.09 mol dm-3. what is the concentration of the barium hydroxide? I like the titration equation Normalitybase*volumebase*concentrationBase equals ...

**acids and alkalis**

hi thanks alot it realy helped me wiv my hwk :D

**physics**

In a room that is 2.13 m high, a spring (unstrained length = 0.30 m) hangs from the ceiling. A board whose length is 1.58 m is attached to the free end of the spring. The board hangs straight down, so that its 1.58-m length is perpendicular to the floor. The weight of the ...

**Math - Bases**

What is 12 base 5? Would you just divide 12 by five and get 2 (but then what about the remainder) If you are refering to logs, 12 base 5 means log of 12 to the base 5. Call it x. 5^x = 12. x = log 12/log 5 (any log base can be used) x = 1.07918/0.69897 = 1.54396 If "5&...

**statics equilibrium**

hey every1, any1 know how to do statics questions? i have a few virtual work questions i have to get right by 2moro or i'll fail my course! please help... There are several engineers here who can assist. At What point from the left end should a uniform meter stick (cg.=50 ...

**business studies**

c----of p---- is the different stages that a product has to pass through before they are sold g----d----p-----is the total value of goods and services produced b a country in a year The first one looks like cycle of production, but I'm not sure about it. The second one ...

**math**

2)How many arrangements of the integers 1,2,3,...,n are there such that each integer differs by one (except for the first integer) from some integer to the left of it? Let's construct the arrangement. First consider 1, it can only have two placed next to it so it has to be...

**Chemistry**

Would heating a tertiary alcohol change its structure and reaction with hydrochloric acid and potassium permanganate (KMnO4)? Tertiary alcohols resist oxidation, but can be oxidised by reagents such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

**Principles of Finance HELP!!!**

Problem 16-7. Pro forma income statement At the end of last year, Roberts Inc. reported the following income statement (in millions of dollars): Sales 3000 Operating costs excluding depreciation 2450 EBITDA 550 Depreciation 250 EBIT 300 Interest 125 EBT 175 Taxes (40%) 70 Net ...

**Science**

How do you measure body volume? I need two ways. Thanks. Displacement is a common method. Fill a barrel full of water, then dunk the body (letting the water overflow), remove the body, and then measure the water level. Another method is to use air displacement, by Air ...

**orientalism of muslim and arab american**

2009 UoP student still stuck on this question...Thanks for all the help. Most of you have graduated or are pretty close by now, but thanks again!

**Accounting**

On January 1, 2006, Mythical purchased some office equipment, paying $24,000. It is anticipated that the equipment will last 4 years and have a zero salvage value at the end of the four years. 1) Make the adjusting entry for depreciation at the end of year two using the ...

**sociology**

I am glad I found this site on accident! I was looking for the same answer to the question about measurements to calculate prejudice! I'm in my second week of ETH 125.....I really like the class. I'm sure I'll use this site again! Good luck everyone!

**Accounting**

1. What is it that the adjustment process actually accomplishes? 2. What would happen to financial statements if the adjustment process was skipped? 3. How does the matching principle relate to the adjusting process?

**Accounting**

Why do revenues increase capital while expenses decrease capital? Because cash is a form of capital.

**Business/Accounting Question**

You are to state what will increase and/or decrease in each of the transactions described below. 1) Mythical Services sold $500 of legal services on account. 2) Mythical collected the $500 from transaction nmuber 1 above 3) Mythical purchased office furniture on account in the...

**chem**

How many moles of ions are there in .2 mol of lithium oxide? I need help again... Strictly speaking, Li2O is a solid and in that form it is not ionized. To get ions from it, you must dissolve it in water, and that causes it to decompose. Despite all that, they probably expect ...

***Chemistry**

Hydrogen reacts w/ sodium to produce solid sodium hydride, NaH. A reaction mixture contains 6.75 g Na and 3.03 g H2. A. Which reactant is limiting? B. What is the theoretical yield of NaH from the above reaction mixture? C. What is the percent yield if 4 g NaH is formed? Laura...

**Chemistry**

A 2.612 g sample of a copper oxide, when heated in a stream of H2 gas, yields .592 g H20. What is the formula of the copper oxide? Again, I need help with this problem. Answer = CuO Ok nvm.. i got it. Set up the reaction as best we can surmise at the moment. CxOy + H2 ---> ...

**Chemistry**

Iron reacts with sulfur to form a sulfide. If 2.561 g of iron reacts with 2.206 g of sulfur, what is the simplest formula of the sulfide? I don't know how to go about doing this problem. The answer is Fe2S3. Calculate the moles of iron in 2.561 grams of iron. Then ...