# Posts by alex

Total # Posts: 3,761

**physics**

Calculate the wavelength (in m) of a photon capable of exciting an electron in Li2+ from the state n= 3 to the state n=5 1.4239*10^-7 - correct

**physics**

ok.. thanks c:

**physics**

Precision refers to the closeness of two or more measurements to each other... Accuracy refers to the closeness of a measured value to a standard or known value.... So would it be precise and accurate?

**physics**

sorry. not precise and not very accurate not precise but very accurate precise and accurate precise but not very accurate (i think its this one)

**physics**

You measure the mass of a 500 g standard on your balance four times. You get values of 455 g, 456 g, 454 g, and 455 g. Which of the following best describes your balance?

**Math**

2 2/5

**Chemistry**

Calculate the maximun=m mass of ethanol that can be made from 5.6 tonnes of ethen

**earth science**

Which of the following is not an example of a mineral crystal shape? A. Pyrite B. Kryptonite C. Quartz D. Calcite i think its A am i right

**Physics**

A small charged sphere,A, carries 4 times the charge of another sphere B. When these are placed 4.5 cm apart, they experience a force of 0.016N attraction between them. Find the charge on B.

**chemistry**

How many milliliters of a 0.100 M NaOH solution are required to neutralize 25.0 milliliters of 0.150 M HCl? Select one: a. 25.0 ml b. 37.5 ml c. 125 ml d. 167 ml

**physics**

Fred and George who are identical twins (same body mass) are competing in aerial skiing. Fred hits the take off with a speed of 20 whereas George has a speed of 8.5. How much higher will Fred go?

**Chemistry**

What quantity of heat is required to convert 200g of ice at 0.00C into water at 50C? I know that im suppose to use the E=mc(Delta T) but im not sure how...

**Algebra**

The height of an object after it is released can be modeled by the function f(t)=-16t^2+vt+s, where t is the n? The height of an object after it is released can be modeled by the function f(t)=-16t^2+vt+s, where t is the number of seconds after the object is released, v is the...

**algebra**

Each person will have exactly the same amount over time because each invested $10,000 at an average interest rate of 7%. Tasha’s investment will yield more over many years because the amount invested at 8% causes the overall total to increase faster. Thomas’s ...

**algebra**

Tasha invests $5,000 annually at 6% and $5,000 annually at 8%. Thomas invests $10,000 annually at 7%. Which statement accurately compares the two investments if interest is compounded annually?

**Algebra**

thanks!!

**Algebra**

A toy rocket that is shot in the air with an upward velocity of 48 feet per second can be modeled by the function f(t)=-16t^2+48t , where t is the time in seconds since the rocket was shot and f(t) is the rocket’s height. What is the maximum height the rocket reaches? ...

**chemistry**

Yes I get it thanks Dr.

**chemistry**

Balance by oxidation method the SO2 + MnO4+H2O --MnSO4+H2SO4+SO4(-2)

**Algebra**

Evan washes two types of vehicles. It takes him 30 minutes to wash a car and 40 minutes to wash a truck. He charges $12 to wash a car and $15 to wash a truck. In 270 minutes, Evan made $105 washing cars and trucks. How many trucks did Evan wash?

**algebra**

A chicken farm orders bags of feed from two farmers. Store X charges $20 per bag, and store Y charges $15 per bag. The farm must obtain at least 60 bags per week to care for the chickens properly. Store Y can provide a maximum of 40 bags per week, and the farm has committed to...

**Algebra**

A sports memorabilia store makes $6 profit on each football it sells and $5.50 profit on each baseball it sells. In a typical month, it sells between 35 and 45 footballs and between 40 and 55 baseballs. The store has no more than 80 footballs and baseballs in stock during the ...

**Math**

Dont know!!!

**pre cal**

what are the real and imaginary zeros of the equation 2x^3 + 5x^2 - 3x + 7

**pre cal**

f(x) = two divided by quantity x squared minus two x minus three Graph A coordinate axis scaled by one. Domain and Range : _____________________ x and y Intercept(s) : _____________________ Horizontal Asymptote(s) : ___________________ Vertical Asymptote(s) : ...

**pre cal**

Choose the point on the terminal side of -45°

**math**

Give an example of a rational function that has no horizontal asymptote and a vertical asymptote at x = 1.

**algebra**

There are 5 red marbles for every 25 blue ones. How many red marbles are there in a group of 600 marbles?

**Highcschool**

Which one of the characters you read about is 12 years old? A. The narrator’s daughter in “The Yellow Wallpaper” B. Ginger Nut in “Bartleby” C. Lily Dyer in “A New England Nun” D. The son of the old man in “The Tell-Tale Heart

**Math**

Action Video rents only action and horror films. Over one 7 day period, they rented 5 horror films for every 9 action films. If they rented 99 action films, what was the mean number of films they rented per day?

**geometry**

Thanks for your help Reiny.

**geometry**

In a triangle, the measure of the first angle is four times the measure of the second angle. The measure of the third angle is 84 degrees more than the second angle. what is the measure of the first angle?

**high school algrebra 1**

Thank You!

**high school algrebra 1**

A youth group is planning a trip to a local amusement park. They are taking a van which holds 10 people. It will cost $25 for parking and tickets to enter the park are $18 per person. create an equation for this situation

**History**

When did the US pull out of the Vietnam War? Some sources say 1973 and then others say 1969..?

**Chem**

Complete and balance the reaction of A) (CH3)2NH(aq)+CH3COOH(aq)→ B) CH3CH2NH2(aq)+HBr(aq)→ C) CH3NH2(aq)+HCOOH(aq)→

**Chemistry!!**

Complete and balance the reaction of A) (CH3)2NH(aq)+CH3COOH(aq)→ B) CH3CH2NH2(aq)+HBr(aq)→ C) CH3NH2(aq)+HCOOH(aq)→

**Physics**

A rock is thrown directly upward from the edge of a flat roof of a building that is 56.3 meters tall. The rock misses the building on its way down, and is observed to strike the ground 4.00 seconds after being thrown. Take the acceleration due to gravity to have magnitude and ...

**SCIENCE HELP !!**

thx ur a life saver

**Science -Check Answers-**

I get conductor but not why you chose insolater. and a series circuit is if all the lights went out all of you are thinking of a parallel circuit

**Science -Check Answers-**

I get conductor but not why you chose insolater.

**physics**

What about how far it has traveled in the time

**Algebra 2**

find the exact value of cos 300 degrees.

**Physical Science**

Thank you both very much!

**Physical Science**

The specific heat of copper is 0.385 J/g.°C. Which equation would you use to calculate the amount of heat needed to raise the temperature of 0.75 g of copper from 7°C to 29°C? a. Q = 0.385 J/g.°C ` (29°C 7°C) b. Q = 0.75 g ` 0.385 J/g.°C ` 29°C ...

**Java Programming**

Oh and ull need to format it, i don't think it will be formatted from here.

**Java Programming**

JUST COPY PAST TO ECLIPSE (OR WHATEVER ELSE U USE) I KNOW THIS WAS POSTED LIKE A WEEK AFTER BUT I DID THIS MOSTLY TO PRACTICE, HOPE IT WAS USEFULL import java.util.Scanner; public class Array { public static void main(String[] args) { //JUST GETTING SOME INPUT FIRST System.out...

**Chemistry**

Calculate molarity of HNO3 please help? Calculate molarity of HNO3 prepared by dissolving 22.3 grams of HNO3 in water to make 875 ml of solution... Please help I'm stuck

**math**

3 bags in 3 bags he will have 6 pounds. If for each bag he needs 5/6 of a pound this means he will have 1/6 x 6 leftover, which is exactly another bag.

**Math**

Can you please help me with this one!! Solve by elimination, 3x+6y=6, 2x-3y=9

**Math**

Solve by elimination: 5x+7y=77 , 5x+3y=53 can you please help me out step by step so I can understand it on my own, thanks.

**Probability**

2) the correct answer is 41/17

**Physical Science**

Which of these cannot increase the strength of an electromagnet? a. making the loops smaller in the coil b. placing an iron bar in the coil c. winding more loops in the coil d. increasing the current in the coil

**Chemistry**

A reaction : A(aq)+B(aq) --> C(aq) has a standard free-energy change of –4.01 kJ/mol at 25 °C. What are the concentrations of A, B, and C at equilibrium if, at the beginning of the reaction, their concentrations are 0.30 M, 0.40 M, and 0 M, respectively? I used ...

**chemistry**

estimate the mass of BaSO4 that will be produced when a 100ml of a 2M solution of Ba(NO3)2 in water is added toa 100ml of a 2M solution of NaSO4 in water

**physics**

a certain hamornic motion has amplitude of 0.7m and a period of 1.3s.find(a)the frequency of oscillation(b)the maximum velocity(c)the maximum acceleration

**Physics 1**

A cart with mass 340 g moving on a frictionless linear air track at an initial speed of 1.5 m/s undergoes an elastic collision with an initially stationary cart of unknown mass. After the collision, the first cart continues in its original direction at 0.42 m/s. (a) What is ...

**Econ**

The process that produces Sonora Bars (a type of candy) is intended to produce bars with a mean weight of 55 gm. The process standard deviation is known to be 0.77 gm. A random sample of 49 candy bars yields a mean weight of 55.82 gm. Find the test statistic to see whether the...

**Physics**

A police car stopped at a set of lights has a speeder pass it at 100 km/h. If the police car can accelerate at 3.6 m/s2, a) how long does it take to catch the speeder? b) how far would the police car have to go before it catches the speeder? c) what would its speed be when it ...

**Algebra 1**

4 pencils and 5 pens cost $2.00; 3 pencils and 4 pens cost $1.58. Write out a system of equations that would represent this situation.

**English**

Ok

**English**

Which description would not apply to a typical metropolis ? A. Bustling B. Crowded C. Large d. Rustic I think it's is A

**English**

Ok I will do that now so I am thinking it A

**English**

A word closely associated with altercation is ? A. revision B. Adherent C. Sensible D. Argument I think it is letter B is that right ? Please answer me

**English**

Ok

**English**

I meant its A

**English**

An invincible team is one that has never know ? A. The joy of victory B. The agony of defeat C. The fear of flying D. Injury or illness I am thinking it could be letter D

**english/vocabulary**

Look back at "failing infrastructure" write a letter to your state representative describing an infrastructure problem in your community and urging swift action. thoroughly describe the problem and it's solution, explaining why it is vital to take action ...

**english/vocabulary**

ok thank you so much for you help i real appreciate it

**english/vocabulary**

can you please help me on word study with writing with idioms ? 1. sick as a dog 2. the best of both worlds 3. under the weather 4. nest eggs 5. when pigs fly 6. slip through the cracks 7. go to seed 8 . thorn in your side 9. turn over a new leaf 10. fifth wheel 11. pitch in ...

**MATH**

THANK YOU FOR HELP ME SO MUCH ON MY HOMEWORK I REAL appreciate it

**math**

you were right i thought so that's why i wrote to you .

**math**

how can you solve this problem ? here X=Y plz help me fast

**physics**

A thin, uniform rod is hinged at its midpoint. To begin with, one-half of the rod is bent upward and is perpendicular to the other half. This bent object is rotating at an angular velocity of 7.1 rad/s about an axis that is perpendicular to the left end of the rod and parallel...

**Physical Science**

13. Why can convex mirrors only produce virtual images? Sadly, I can't find this answer in my book. :( Any help would be appreciated, please and thank you!

**Math help**

A catapult launches a boulder with an upwark velocity pf 184 feet per second. the heigh of the boulder in feet after t seconds is given by the function h(t)=-16t^2+184t+20. how long does it take the boulder to reach its maximum height? What is the boulders maximum height? ...

**Word problem**

Mrs sue or Damon am I correct?

**Word problem**

. A catapult launches a boulder with an upwark velocity pf 184 feet per second. the heigh of the boulder in feet after t seconds is given by the function h(t)=-16t^2+184t+20. how long does it take the boulder to reach its maximum height? What is the boulders maximum height? ...

**Equations**

How many real number solutions does the equation have y=3x^2+18x+27 none one two infinite

**Equation help 2 questions**

Mrs sue can you help me with question 2?

**Equation help 2 questions**

is number 1 none?

**Equation help 2 questions**

How many real number solutions does the equation have y=-4x^2+7x-8 none one two infinite How many real number solutions does the equation have y=3x^2+18x+27 none one two infinite Thank you!

**math**

20ft

**Equation help**

can someone help?

**Equation help**

A physics student stands at the top of a hill that has an elevation of 56 meters. he throws a rock and it goes up into the air and then falls back past him and lands on the ground below. The path of the rock can be modeled by the equation y=0.04x^2+1.3x+56 where x is the ...

**UCF**

What will be the change in enthalpy when 100.0 g of butane, C4H10, is burned in oxygen as shown in the thermochemical equation below? 2 C4H10(l) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) ΔH = −5271 kJ −2636 kJ −4534 kJ −9087 kJ −1.817 × ...

**trig**

a hot air balloon climbs continuously along a 30° angle to a height of 5,000 feet. To the nearest tenth of a foot, how far has the balloon traveled to reach 5,000 feet? Draw a sketch and then solve.

**chemistry**

A is the central atom and B is an atom bonded to the central atom. n is the number of B atoms.

**chemistry**

2 is linear. 3 is trigonal. 4 is tetrahedral. 5 is trigonal bipyramidal. And 6 is octahedral.

**Geometry**

I need help!!! a hemispherical bowl with radius 25cm contains water whose depth is 10cm. what is the water's surface area

**US history**

Would question 4 be B instead?

**US history**

True False The divorce rate in America declined in the 1920s. false right? All of the following were anti-modern reactions except A.fundamentalism B. Ku Klux Klan C. cultural anthropology D. arts and crafts movement E. prohibition F. None of the above Is it D? Fundamentalists ...

**Math 110**

I don't understand how you got 2016. I understand how you added to get the 1,9, 11, and 6. But I do not understand where you got the 1->2, 9->0, and 11->1.

**DATABASE.PLEASE!!**

CAN ANYONE DIRECT ME HOW TO EXTRACT A BUSINESS RULE AND RELATIONSHIP FROM THIS PARAGRAPH.? *I KNOW ITS MANY TO MANY RELATIONSHIP. BUT I STILL HAVE PROBLEM TO COMPLETELY BREAK THE RELATIONSHIP DOWN TO ONE TO MANY. PARAGRAPH: Students will also be required to sit for many tests...

**Geometry**

I need help in this problem: A 14-foot ladder is leaning against a house so that its top touches the top of the wall. the bottom of the ladder is 8 feet away from the wall. which of these can be used to find the height of the wall? A. in a right triangle with 14-foot leg and ...

**Chemistry**

The measured potential of the following cell was 0.1776 volts: Pb|Pb2+(??M)||Pb2+(1.0M)|Pb Calculate the electrode potential of the unknown half-cell(anode). Not sure how to approach this, considering the molarity is unknown. There isn't a lot of space on the page for the ...

**Equation help**

Anyone?

**Equation help**

X^2-6x+7=0 1.-1.59,4.41 2.-1.59,-4.41 3.1.59,-4.41 4.1.59,4.41 Can someone help?

**Equations Help**

is this the answers for both of them?

**Equations Help**

ok I get that one