Science & Mathematics - 27 September 2007

calculate molality and molarity.
Molar mass of H2SO4 is 98g/mol.
plz solve this problem and plz explain what does 15%H2SO4 means.

2007-09-27 02:59:42 · 5 answers · asked by cmpunkbohemia 1 in Chemistry

2007-09-27 02:54:34 · 1 answers · asked by lasmom1223 1 in Chemistry

1. the properties of a compound are __ the properties of the elements that form it.
A. similar to
B. different from
C. identical to
D. derived from

2. reactions between atoms involve only __.
A. valence electrons
B. inner electrons
C. neutrons
D. protons

3.oppositely charged ions attract each other, forming a(n) __ bond.
A. covalent
B. crystal
C. ionic
D. molecular

4. the formula for iron (lll) oxide, Fe2Cl3, shows that one unit of the compound contains __ iron atoms.
A. 2
B. 3
C. 5
D. 6

5. two atoms of bromine react with each other to form a(n) __ bond.
A. covalent
B. ionic
C. crystal
D. molecular

6. noble gases are sometimes used to protect valuable documents because they are __.
A. molecular
B. totally inert
C. unreactive
D. unstable

7.when reacting with an atom of fluorine, an atom of lithium will lose an electron and become a lithium __.
A. compund
B. crystal
C. ion
D. molecule

2007-09-27 02:49:57 · 3 answers · asked by Anonymous in Chemistry

When its..

is poured onto another substance
mixes with water
dissolves another substance
or
changes from one state of matter to another

2007-09-27 02:46:35 · 1 answers · asked by Anonymous in Chemistry

I live in the U.S.A. in Oregon and I saw a really bright star or planet right before sunrise in the east and am wondering what it is.

2007-09-27 02:44:08 · 6 answers · asked by Andrew V 2 in Astronomy & Space

Why can samples of solutions often be separated into their compenents by chromatography?


I'm not sure how to explain this. Can anyone help PLEASE thanks sooo much!!!

2007-09-27 02:38:43 · 4 answers · asked by Natlsn12009 1 in Chemistry

2007-09-27 02:35:24 · 1 answers · asked by Anonymous in Chemistry

Water "softeners" remove metal ions such as Fe2+, Fe3+, Ca2+, and Mg2+ (which make water "hard") by replacing them with enough Na+ ions to maintain the same number of positive charges in the solution. If 6.5 103 L hard water is 0.015 M Ca2+ and 0.0010 M Fe3+, how many moles of Na+ are needed to replace these ions?

2007-09-27 02:34:42 · 1 answers · asked by ronnie c 1 in Chemistry

I mean,we add those numbers that we put in front of each element to balance the equation,for example the reactants,the sum of the numbers that we put to balance the equation is 5,and for the product is 4,,,why?but without multiplying it only adding those numbers...

2007-09-27 02:30:47 · 1 answers · asked by Anonymous in Chemistry

lol everyone's answers have been so helpful when i asked about physics yesterday i thought id throw one more out there

this one is pretty simple, i think.. its just that neither my textbook OR the notes from class show an example similar to this, so i dont really know where to start...

"a child slides down a slide with a 28 degree incline, and at the bottom her speed is precisely half of what it would have been if the slide had been frictionless. Calculate the coefficient of kinetic friction between the slide and the child."
i might need to use

force of friction = coefficient of kinetic friction x normal force

but idk an equation that relates with angles!

2007-09-27 02:29:25 · 5 answers · asked by Anonymous in Physics

if so what will happen if it stops rotating?will it become a sphere? or be like that

2007-09-27 02:23:01 · 9 answers · asked by HARI 1 in Astronomy & Space

2007-09-27 02:20:57 · 6 answers · asked by Anonymous in Engineering

I'm guessing that there needs to be something inside to stop the bucky ball from collapsing

2007-09-27 02:17:45 · 9 answers · asked by vEngful.Gibb0n 3 in Other - Science

2007-09-27 02:17:34 · 1 answers · asked by Anonymous in Chemistry

Do violent areas like the Middle East have more Ghosts?After death,do spirits hold on to Earthly resentments?Would Moslem Ghosts and Jewish Ghosts still hate each other?

2007-09-27 02:13:40 · 14 answers · asked by Dr. NG 7 in Paranormal Phenomena

Truthfully!

2007-09-27 02:13:20 · 28 answers · asked by MuffDvr 3 in Chemistry

2007-09-27 02:05:05 · 1 answers · asked by Shival G 1 in Chemistry

2007-09-27 02:03:10 · 2 answers · asked by Jackie 4 in Physics

which of the following equations expresses the total cost (c) of printing t number of shirts?

2007-09-27 01:56:07 · 2 answers · asked by Shival G 1 in Mathematics

2007-09-27 01:54:51 · 2 answers · asked by Sniper of Goth 4 in Other - Science

no freaky answers

2007-09-27 01:54:12 · 5 answers · asked by charm 1 in Astronomy & Space

2007-09-27 01:53:29 · 8 answers · asked by Louise J 1 in Mathematics

Help me solve this equation using susbtitution....?

2007-09-27 01:40:02 · 9 answers · asked by Anonymous in Mathematics

Not sure how to approach this, any ideas?

The purchasing power of the 1983 dollar is modeled by P(t) = 3.818e^-0.0506t where t is the number of years after 1960. In what year will the purchasing power of the 1983 dollar be $0.25?

2007-09-27 01:35:33 · 2 answers · asked by Anonymous in Mathematics

2007-09-27 01:34:07 · 6 answers · asked by CN 2 in Weather

The number of stamps that May and Henry had at first was in the ratio of 3 : 1. After May bought 36 stamps and Henry sold 20 stamps, May then had 5 times as many stamps as Henry. How many stamps did Henry have at first? The answer is 68. But I do not know the steps. Can someone help, but pls do not use algebra. thks!

2007-09-27 01:33:25 · 2 answers · asked by evabree 1 in Mathematics

Xavier, Yati and Zachary shared some marbles. Xavier had 1/3 of what Yati and Zachary had. Yati had 1/5 of what Xavier and Zachary had. Xavier had 24 fewer marbles than Zachary. How many marbles do they have altogether? Answer is 72 but I do not know the steps. Can someone help, pls do not use algebra. thks!

2007-09-27 01:30:20 · 1 answers · asked by evabree 1 in Mathematics

If a piece of cucumber is placed on the table for a few days, itbecomes soft. But it becomes hard andturid again if its cut end is immersed in water. Explain why the cucumber behaves in this manner.

this is aquestion related to diffusion and osmosis and maybe active transport too, but I don't know the answer!!!!

2007-09-27 01:29:28 · 7 answers · asked by Mia S 1 in Biology

Give the definite integral from 0 to infinity of cos x / sqrt{x} dx. (ie the function is x^{-1/2} cos x..

2007-09-27 01:05:07 · 1 answers · asked by Anonymous in Mathematics

2007-09-27 01:01:01 · 4 answers · asked by E.S 1 in Weather