# Tasks for topic two for those who dont have it like danni

a) we did this one in class....
which of the following 4 statements describes isotopes?
the answer we did in class too. it is
ii) atoms of an element having different 3s of neutrons
iv) 90 SR 38 and 92 SR 38

b) (1) neon has three isotopes 22. 21, 20 with abundances of 8% 2% and 90% find relative atomic mass.
(2) rubidium 85 and 87 with ratio of 72:28 find atomic mass
(3) Ga 69 71 ratio of 62:38 calculate atomic mass
(4) Cl2 has massses of 70, 72, 74 ratio of 9:6:1 what is avg. atomic mass? wut is relative abundance of 35Cl and 37Cl isotopes?

c) (1)plot a graph for the table... here's teh table it's for lead in a radioactive reaction. plot graph and find half-life
time/ hour 0 1 5 10 25 50 75 100
cnt/minute 300 296 285 270 228 175 133 103
(2) t=26 days 1/16= final amount what is half-life
(3) Radon 1/2 life=36.0 min. what fraction of the original quantity remains after i) 360 min ii)1080 min.
(4) C^14 1/2 life= 5580 yrs 5g sample from newly cut lumber has 2.02 counts/sec. a 5g relic sample has a count of 1.81 counts/sec. find age of relic
(5) t=3hrs. initial count=1100 c.p.m final count=778c.p.m what is half life?

D)name and show the charge of the ions present in the ex)
i) NaCl
ii) SrO
iii) AlN
iv) BaCl2
v) K2 O (one compund 2 goes w/ the K)
vi) CuO
vii) Cu2 O (1 compound)
viii)Iron (III) Chloride

E) Write the formula or names for the following compuounds
i) Dinitrogen tetroxide
ii) N2O5
iii) PCl3
iv) Phosphorous pentachloride
v) SF6

thank you danielle for writeing this all out, and for darin for doing the lazy (but smart) thing of just scanning it to me. you both rock
<3danni
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