19. A radioactive nucleus decays to yield a bismuth-211 nucleus and an alpha particle. What was the identity of the original nucleus? Show the nuclear equation that leads you to this answer.
November 21, 2014
in passing theough a wooden block 8cm thick the velocity of a beullet reduces from 700m/s to 300 m/s if the mass of the bullet is 10g find the average resitance to penetrate ?
November 4, 2014
sulfuric acid is a strong acid and dissociates in water as shown in reaction H2SO4(aq)=2H^+(aq)+SO4^2-(aq) what is the hydrogen ion concentration, in mol dm^-3,when 1.50g of sulfuric acid is dissolved in water to give 0.500dm^3 of solution ?show all of your working and give ...
December 30, 2012
A bouncy rubber ball is dropped from a height of about a metre above the ground .it falls to the ground, bounces and then rises back to almost the height from which it was dropped. Describe the main energy transformations that take place from the point at which the ball first ...
December 21, 2012
Science need help
Astronomers believe that the biggest stars in the Galaxy may be a hundred times more massive than the Sun, but are a million times brighter. Would you expect such stars to have longer, shorter or comparable lifetimes to that of the Sun?
December 21, 2012
What is the entropy change to the surroundings when 1 mol of ice melts in someones hand if the hand temperature is 32°C? Assume a final temperature for the water of 0°C. The heat of fusion of ice is 6.01 kJ/mol. a. 188 J/K d. b. 22.0 J/K c. 19.7...
August 2, 2012
What is the entropy change to the surroundings when 1 mol of ice melts in someones hand if the hand temperature is 32°C? Assume a final temperature for the water of 0°C. The heat of fusion of ice is 6.01 kJ/mol. a. 188 J/K d. +19.7 J/K b. 22.0 J/K e...
August 1, 2012
If 1 mol of ice melts at its melting point of 273 K, the entropy change for the ice is 22.0 J/K. If the ice melts in someones hand at 34°C, what is the change in the entropy of the universe? Assume a final temperature for the water of 0°C. The enthalpy of fusion ...
July 30, 2012
Calculus urgent help
evaluate the limit as x approaches infinity for the absolute value of (the square root of xsquared+x) -x i think the answer is 1/2 from my calculator but I have to show how i got it algebricallly and have no clue what to do
September 27, 2010
Hi, I have few problems that I really need help solving. I think I start out right but get messed up along the way and get the wrong answer...Any help is appreciated! thank you so much! find derivative of: 1) y=arctan 2^x 2) arctan(xy)= 1+x^2y Also... 3) find the equation of ...
March 10, 2009
Question: "Plutonium isotope Pu-239 has a half-life of 24,100 years. Suppose that 10 grams of Pu-239 was released in the Chernobyl nuclear accident. How long will it take for the 10 grams to decay to 1 gram?" I know that I am suppose to use y= ye^kt , to get the ...
February 26, 2009
hi, I'm having trouble differenciating between direct object pronouns and indirect object pronouns. To say: "bears scare me" is that direct object pronoun? So it would be "los osos me asustan"? To say: "they(bears) scare them" is that still ...
October 18, 2008
I have an assignment where I am suppose to find any recent situation that shows how the Eurpean union (or european nations) are in touble of credit crunch. I'm not quite sure what credit crunch is and how the EU is suffering through (or did?) one recently. Can you please ...
September 27, 2008
what are three important US domestic politics(domestic events/issues) from the 1990s? I have been searching for the answer, but I keep on only finding foreign politics and not domestic ones and the domestic issues I do find are not from 1990s...someone please help me!!
May 30, 2008
Out of all the different civilizations, which one is the least known ? Since you're asking about the "least known" civilization, there aren't going to be many (if any) answers -- since people don't know about it! If you search Google for "little ...
April 1, 2007