Science & Mathematics - 2 October 2007

6. Which of the following are definitely in atoms of the same element?
*A. 3 protons, 3 neutrons and 3 protons, 4 neutrons
B. 3 protons, 3 neutrons and 4 protons, 4 neutrons
C. 4 protons, 4 neutrons and 3 protons, 4 neutrons
D. 3 protons, 4 neutrons and 4 protons, 3 neutrons

7. An atom of iron contains 26 electrons. How many energy levels are needed to contain these electrons?
A. 1
B. 2
C. 3
*D. 4

8. The atomic number of chlorine is 17. How many valence electrons does an atom of chlorine have?
A. 2
*B. 7
C. 8
D. 17

9. Which of the following is an example of periodicity?
*A. eating breakfast
B. hitting a home run
C. writing a letter
D. sneezing

10. A certain element is a gas and does not conduct electricity or heat. Which of the following is a possible number of valence electrons for the atoms of this element?
A. 1
B. 2
C. 3
*D. 6

11. Based on its position in the periodic table, the most likely charge of an iodine ion is?
*A. 1+
B. 1-
C. 2+
D. 7-

2007-10-02 08:11:02 · 2 answers · asked by Anonymous in Chemistry

http://answerboard.cramster.com/physics-topic-5-108662-0.aspx

2007-10-02 08:10:53 · 2 answers · asked by Anonymous in Physics

I have to do this equation step by step...I have a few answers but I don't understand what is happening in each step...can someone solve this equation and explain step by step what is happening....so far I have 2 different answers...

1) cosh(x) = 0...but it can't equal 0 (why?..i don't understand)

2) people sustituted the cosh(x) for a 1, then solved the equation...WHY did they substitute the cosh(x) for a 1...what's the rule there...

Thank you...

2007-10-02 08:10:01 · 3 answers · asked by Gary S 1 in Mathematics

My math teacher told me to find these but I cannot figure it out. Can someone help me? I have tried a whole bunch of different ways, including changing to decimals, and radians etc., but I cannot find how to get the answer.

I know the answers are 4/5 and -4/5, but I need to know how to get there.

2007-10-02 08:09:37 · 2 answers · asked by mark p 2 in Mathematics

NO TWO SNOWFLAKES ARE ALIKE.

A container has an infinite number of snowflakes. I randomly pick 1 snowflake from this container. What is the probability that my snowflake is unique?

2007-10-02 08:09:33 · 9 answers · asked by Dr D 7 in Mathematics

1. Which of the following is not an example of a model?
*A. a floor lamp
B. a globe
C. a road map
D. a wind tunnel

2. A 1-g sample of the compound hydrogen chloride was analyzed and found to be 2.74 percent hydrogen and 97.3 percent chlorine. What percentage of hydrogen is present in a 2-g sample of hydrogen chloride?
A. 1.37%
*B. 2.74%
C. 5.48%
D. 97.3%

3. The atomic number of an element whose atoms have 9 electrons and 1 neutrons is?
*A. 9
B. 19
C. 1
D. 18

4.One isotope of carbon has 6 protons and 6 neutrons. The number of protons and neutrons of a second isotope of carbon would be?
A. 7 and 6
*B. 6 and 7
C. 7 and 7
D. 6 and 6

5. If 9. g of water contain 1.0 g of hydrogen, what mass of oxygen is contained in 36 g of water?
A. 4.0 g
B. 8.0 g
C. 10.0
*D. 32 g

2007-10-02 08:09:11 · 2 answers · asked by Anonymous in Chemistry

a. It will be able to gather more mass
b. Condensation will be less effective
c. It will be able to gather lighter materials and gases
d. Both a and b
e. Both b and c
f. All of the above

2007-10-02 08:06:24 · 3 answers · asked by investing1987 3 in Astronomy & Space

a. Emission
b. Absorption
c. Continuous

2007-10-02 08:04:00 · 2 answers · asked by investing1987 3 in Astronomy & Space

I am having a difficult time deciding on what I should take. I have been taking classes for the Nursing program, but wonder if the Surgical Tech program is better for me. Is there anyone out there that knows anything about the Surgical Tech program and can give me some advice? Thanks!

2007-10-02 07:58:22 · 12 answers · asked by hotmama 3 in Medicine

17. Nitrogen atoms each have five valence electrons. How many pairs of electrons must be shared in a molecule of N2?
A. 1
B. 3
C. 4
D. 6

18. A tug-of-war in which neither side is able to move the other side could be used to model a(n) __.
A. covalent bond
B. crystal
C. ionic bond
D. transfer of electrons

19. A white solid is heated in a test tube. The solid slowly changes color to a grayish power, and a gas escapes from the test tube. Is the white solid an element of a compound?
A. t must be an element since it underwent a chemical change
B. It must be an element since it underwent a physical change
C. It must be a compound since it broke down into two new substances
D. Cannot be determined

20. Find the error in the equation and correct it so the equation would be correctly balanced:
Ca(s) + 2H2O(l) --> CaOH2(aq).
A. Ca2(s)
B. H2O(l)
C. Ca(OH)2(aq)
D. both b and c

2007-10-02 07:58:20 · 5 answers · asked by Anonymous in Chemistry

How is it extracted - is it mined or dug?

2007-10-02 07:57:23 · 12 answers · asked by Anonymous in Earth Sciences & Geology

2007-10-02 07:56:39 · 1 answers · asked by Anonymous in Chemistry

Why wouldn’t this work???
Design fuel storage tanks that fit in cargo area of space shuttle. Launch extra fuel in unmanned rockets to space station.
Have space shuttle launch and dock at space station… fullup extra fuel tanks. Then use shuttle to fly back to moon? With much lower gravity, shouldn’t the shuttle be able to break gravitational pull of moon and return to Earth?
Wouldn’t this be both cost effective and much faster than 10 years to design a vehicle to go back to the moon? (On a slightly different note… why did it take 7 years to get there the first time, but 10 years after 30 years of technological advances?)
BTW, please don’t respond with “Makes too much since… so they would never do it!” :)

2007-10-02 07:55:00 · 8 answers · asked by Mickey W 2 in Astronomy & Space

I asked the Q: 'why do you see stars better from the corner of your eye than if you look at it directly?' -- is it to do with the blind spot

i now know that it is definitely the fovea (area in the retina with the most light- sensitive cells) that creates this - but how/why? (details?)

2007-10-02 07:54:36 · 3 answers · asked by Anonymous in Biology

what would you multiply "molecules of N2O" by to get the units "grams of N2O" ?

2007-10-02 07:53:31 · 2 answers · asked by sunnydaze34509xoxo 2 in Chemistry

2007-10-02 07:51:40 · 7 answers · asked by Jax Back 3 in Physics

Maybe at the edge of the universe or something..........

2007-10-02 07:51:07 · 2 answers · asked by Anonymous in Physics

a. Less than or equal to -1
b. between 0 and 1
c. greater than or equal to 1

2007-10-02 07:50:40 · 8 answers · asked by missy1525 1 in Mathematics

2007-10-02 07:49:14 · 50 answers · asked by Anonymous in Astronomy & Space

7x2 + 49x + 42

2007-10-02 07:48:31 · 5 answers · asked by alton l 1 in Mathematics

11. Calculate the frequency of yellow light if its wavelength is 600 x 10^-9 m. Show all the steps used in your calculation.

12. Calculate the wavelength of radio waves if their frequency is 5 x 10^6 Hz. Show all the steps used in your calculation.

2007-10-02 07:47:41 · 1 answers · asked by Binky 3 in Astronomy & Space

Just done an experiment on ldrs. for some reasont he ohmage is coming out higher under extreme light. maybe i am just confused but the equation to wort out resitance would be r = v/i would it not.

My results for two volts on a power pack are 0.02 a and 3.47 v under bright light. this gives a big ohm reading but surely it should be smaller. it just doesnt make sense to me so any help would be appreciated.
Any advice on ldrs and resistors in a context of how and the theory of why they resist would be awesome.

Many Many thanks

2007-10-02 07:47:25 · 2 answers · asked by master 2 in Physics

I need to know about 5 other ways of powering satellites other than solar power, please help.

2007-10-02 07:46:43 · 1 answers · asked by TiMiTiM 1 in Astronomy & Space

2007-10-02 07:43:15 · 1 answers · asked by Anonymous in Biology

for my science homework...

2007-10-02 07:38:46 · 3 answers · asked by Anonymous in Mathematics

2007-10-02 07:38:36 · 1 answers · asked by Anonymous in Chemistry

anyone know what this is? I am near detroit, MI...looking to the east in the early morning (5-6 am) there has been what looks like a very bright star very low lying in the sky. With binoculars, you can see tiny bright objects near this star...By the looks of it, it is a planet, and the small bright things are moons, does anyone know for sure what it is?

2007-10-02 07:38:02 · 9 answers · asked by Anonymous in Astronomy & Space

I am trying to answer sec2x = 2 / √3

I did
1/cos2x = 2/√3
√3/2 = cos2x

Then I put cos-1(√3/2) in my calculator and got a math error, what am I forgetting?

2007-10-02 07:37:48 · 1 answers · asked by biscuit.heads 2 in Mathematics

2007-10-02 07:37:31 · 1 answers · asked by Anonymous in Chemistry

2007-10-02 07:36:46 · 4 answers · asked by the ugly truth 2 in Chemistry