Wednesday
June 19, 2013

# Posts by Davis

Total # Posts: 91

basic chem
1)an atom has a mass number of 27 and 14 neutrons. what is the atomic number of this atom? 2)The atomic number of fluorine is 9. What is the mass # of a fluorine atom with 8 neutrons?

Chem
oh okay i get it now, thank you! Why did you subtract 1.00 from the abundance though? how do you know?

Chem
(79.904)=(80.9163)(0.4931) + x(0.4931) 79.904=39.90 + 0.4931x 40.004=0.4931x x=81.13amu

Chem
My teacher said the answer is 78.92 amu and 50.69%. But i keep getting 81.13amu and i don't know how to get the percentage.

Chem
Bromine has two natural occurring isotopes (Br-79 and Br-81) and has an atomic mass of 79.904 amu. The mass of Br-81 is 80.9163 amu, and its natural abundance is 49.31%. Calculate the mass and natural abundance of Br-79.

algebra
Oh and then you put your equation in slope intercept form y=mx+b. and get -7y=-6x-42 and divide by 7. so your line will be y=6/7x +6.

algebra
you plug in zero for x and get 6(0)-7y=-42 and then you get-7y=-42 which is y=6. and then you plug in zero for y and get 6x-7(0)=-42 and then you get 6x=-42 which is x=-7. so your points are (-7,6) and then graph them.

trig
5sin^2 270degrees -3cos180degrees-tan(-180degrees) i got -2 but I'm not sure if i did it right?

math
That's not possible. But 10^-1 is. You move your decimal to the left for negative exponents and you move your decimal to the right for positive exponents. If you had a value of 1 X 10^-2 for example you would move your decimal two places to the left which would equal .01 i...

trig
oh okay! I get it now, thanks!:)

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