DC

Most popular questions and responses by DC
  1. Chemistry

    help - confusion :( The oxidation of copper(I) oxide, Cu2O(s), to copper(II) oxide, CuO(s), is an exothermic process, 2 Cu2O + O2 --> 4CuO The change in enthalpy upon reaction of 75.30 g of Cu2O(s) is -76.83 kJ. Calculate the work, w, and energy change,

    asked on November 3, 2013
  2. Chemistry

    A mineral sample is analyzed for its cobalt and calcium content. A sample is dissolved, and then the cobalt and calcium are precipitated as Co(OH)2(s) and Ca(OH)2(s). At what pH can Co(OH)2(s) be separated from Ca(OH)2(s) at 25 °C? Assume that an

    asked on November 2, 2013
  3. Math

    azmin decided to get some exercise by taking the stairs from the first to the fifth floor in her apartment building. The first time she went up the entire flight, she walked up some steps and ran up 16 steps. This took a total of 60 seconds. The second

    asked on October 29, 2015
  4. math

    In a grand prix automobile race, Speedy Ryder averaged 110 miles per hour for the first half of the course and 130 miles per hour for the second half of the course. Cannonball Carter maintained a constant speed of 120 miles per hour throughout the race.

    asked on December 3, 2015
  5. Algebra

    Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 80 people. (a) How many would you expect to be between 167 and 183 cm tall? (b) How many would you expect to

    asked on December 21, 2012
  6. Chemistry

    I would really appreciate some help with this thermochemistry problem! I'm really confused as to why I keep getting the wrong answers... I have gotten w=-1.305kj and energy change = 78.13kj... both of which were marked wrong. Here's the question: The

    asked on November 3, 2013
  7. physics

    A 34-kg girl is bouncing on a trampoline. During a certain interval after leaving the surface of the trampoline, her kinetic energy decreases to 220 J from 480 J. How high does she rise during this interval? Neglect air resistance.

    asked on November 4, 2013
  8. Algebra

    A club consists of 16 men and 19 women. In how many ways can they choose a president, vice president, treasurer, and secretary, along with an advisory committee of six people? (Round the answer to five decimal places.) _____ x 10(to the 11th power) ways

    asked on December 21, 2012
  9. math

    carmen is a girl scout camp counselor and needs to assign scouts to tents. She noticed that if two scouts were assigned to each tent then six girls would have no tent. On the other hand, if four scouts were assigned to each tent then there will be three

    asked on December 3, 2015
  10. math

    The entire second grade at Sunshine Elementary participated in a single elimination checkers tournament. There are a total of 118 second graders and so there were 59 matches in the first round of the tournament. In the second round,the 59 remaining

    asked on October 30, 2015
  11. business

    Consider the wide spectrum of business organizations, ranging from gigantic corporations to working at home. Describe at least three types of business organizations that you are familiar with or that you would like to know more about. How is each one

    asked on May 4, 2010
  12. math

    Tasha’s school bus usually drops her off in town every day at 4pm and her mother picks her up at the bus stop. Last Friday was a short school day, only Tasha’s mother forgot so she wasn’t at the bus stop when Tasha was dropped off an hour early, at

    asked on November 10, 2015
  13. Math

    Multiply. write each product in simplest form. 3 7/10 X 7

    asked on October 9, 2016
  14. math common core

    1/4 pages typed per minute how many pages can be typed in 18minutes

    asked on September 27, 2016
  15. geometry

    If Dave is 6 feet tall and casts a shadow of 15 feet, what is the height of a tree that casts a shadow of 81 feet? Draw a diagram and solve for the height of the tree.

    asked on May 21, 2014
  16. Chemistry

    A canister holds a gas at 16.3 psi when the temperature is 15˚C. To what will the pressure change when the temperature is increased to 20˚C? *

    asked on April 17, 2013
  17. Chemistry

    10.7 L of a gas at 1.75 atm are expanded to 20.0 L at a constant temperature. What is the new gas pressure? *

    asked on April 17, 2013
  18. Math

    Twelve people serve on a board and are considering three alternatives: A, B, and C. The choices followed by vote is shown in following table. Determine the winner, if any, using a Borda count. (ABC) 2 (ACB) 4 (BAC) 2 (BCA) 1 (CAB) 2 (CBA) 1 The winner is

    asked on December 21, 2012
  19. college

    Evaluate the difference quotient for the given function. Simplify your answer. f(x) = 3 + 5x − x2, f(4 + h) − f(4) h

    asked on September 11, 2011
  20. math

    two cars are approaching each other on the same highway one from san bernardino at 80 mph and the other from las vegas at 60 mph how far apart are they on the highway one hour before they meet?

    asked on November 10, 2015
  21. Algebra

    The campus vets club is having a raffle and is selling 2,700 tickets. If the people on your floor of the dorm bought 297 of those tickets, what is the probability that someone on your floor will hold the winning ticket? (Enter your answer as a decimal.)

    asked on December 21, 2012
  22. math

    (9x^4+0x^3+8x^2+17x-20)÷(-3x-4)

    asked on February 24, 2011
  23. Maths

    The projection of a line on axes are 6,2,3. What will the direction cosines of the lines be?

    asked on October 21, 2016
  24. physics

    if i travel in a bus which have 40km/hour speed than i through a coin in vertical hight. Does the coin fall in my hand

    asked on June 28, 2012
  25. living life a health life

    what are the three methods by which HIV and AIDS are usually transmitted?

    asked on June 27, 2012
  26. math

    The sum of the page numbers on the facing pages of a book is 457. Find the page numbers?

    asked on November 15, 2010
  27. chem

    method of producing aspirin

    asked on March 13, 2008
  28. ss

    what type of fallacy 12. That's gotta be a great line of clothes. Have you seen the prices and the people endorsing it? 8. Michael Jordan wore that brand, so those must to be the best basketball shoes. (FALSE ANALOGY) 5. All right-thinking people will

    asked on January 20, 2008
  1. Math

    idk

    posted on September 3, 2018
  2. Maths

    Here, P=Q-1 Now, P-Q = Q-1 - Q = -1 Therefore, P-Q=-1

    posted on October 21, 2016
  3. Maths

    10

    posted on October 21, 2016
  4. Math

    x>55

    posted on September 5, 2016
  5. Biology

    ribosome structure

    posted on May 27, 2016
  6. physics

    71

    posted on November 19, 2015
  7. Physics

    ,,,,,,

    posted on March 26, 2014
  8. Chemistry

    ok I recalculated and got the w=.006523kJ and the energy change to be -76.82kJ... The energy change is right but the w is wrong for some reason... I calculated w as w=-delta(n)RT = -(0-.26312molO2)(8.314452x10^-2 Lbarr/molK)(25+273.15) =

    posted on November 4, 2013
  9. Chemistry

    Thanks Dr.Bob!! I was then able to plug into the second equation and found the concentration of calcium! You were great help! Thanks again :)

    posted on November 2, 2013
  10. Chemistry

    These are the given Ksp values to use: Ksp of Co(OH)2 is 5.9x10^-15 M^3 Ksp of Ca(OH)2 is 5.0x10^-6 M^3

    posted on November 2, 2013
  11. Chemistry

    A canister holds a gas at 16.3 psi when the temperature is 15˚C. To what will the pressure change when the temperature is increased to 20˚C? *

    posted on April 17, 2013
  12. Math

    Thank you Ms. Sue - Happy Holidays to you!

    posted on December 21, 2012
  13. Math

    (ACB)24

    posted on December 21, 2012
  14. Algebra

    You're awesome, thank you much and Happy Holidays to you!

    posted on December 21, 2012
  15. Algebra

    You're awesome, thank you much and Happy Holidays to you!

    posted on December 21, 2012
  16. Algebra

    Thank you so much for your response. Just to be clear are you saying I need to multiply .8176 x 80 and then .7977 x 80?

    posted on December 21, 2012
  17. Math

    5w=42

    posted on April 16, 2012
  18. LIfe orientation

    5 ways : Water and sanition , Population

    posted on May 9, 2011