Saturday
April 19, 2014

Posts by Zak


Total # Posts: 26

chemistry
i have some question but i can not post it ,what should i do .help

chem
how many moles of Na are there in 1.50 moles of NaCl ?

chemistry help
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 yo...

PHISIC help
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 ...

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?

Math
It's right because 5x5x5=125 and 125x2=250

Measurement
Can anayone tell me something that is 65 mm long or wide?

Calculus
1. Does the limit limx-->0:6[[x]] exist? 2. Does the limit limx-->3[[x]] exist? [[x]] is less or equal to x.

chem
What is the entropy change to the surroundings when 1 mol of ice melts in someone’s 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...

CHEMISTRY
What is the entropy change to the surroundings when 1 mol of ice melts in someone’s 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. ...

Chemistry
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 someone’s 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 ...

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

chemistry
it is a method of which you use to do scientific projects and stuff. its the order in which you write the information.im not exactly sure of the order though

Math
Paul is 12. His father is 33. How many years ago was the father 4 times as old as the son?

Physical Science
11. Chromium is produced by reacting its oxide with aluminum. If 76g of Cr2O3 and 27g of Al completely react to form 51g of Al2O3, how many grams of Cr are formed?

social studies: geography
What feature makes up part of the U.S border with Canada? What feature makes up much of the U.S border with Mexico?

socialstudies
what conditions drew people to the tigris-euphrates vally

AP Calc
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 t...

calculus
Ohhh, I get it!! Thanks so much, you helped me a lot! :)

calculus
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 equa...

spanish
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 di...

economics
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 e...

history
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!!

environmental science
what is the range of tolerance of physical and chemical conditions for giant pandas?

history
what does popular consent mean???

civilizations
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 know...

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