Page 498 - Chemistry eBook

c c
h o
h
p e
N
a e
e
d d d -
232Th → 4He 􏰀 X
tor of 10 ctor of 100
tor of 100
e same soluti ndicator. All t
mcresol gree e pH of the s
(3) 7.8 (4) 9.9
le of NaOH( rs of 0.50 M
aOH(aq)?
(3) 0.25 (4) 0.50
taneously e , but radi
d from hydr i. Which hy
H-2, only H-3, only H-3, only
2, and H-3
on a ree i n, an olutio
aq) i HCl
M M
mitted from tion
ogen droge
(2) 2H2 􏰀 O2 → 2H2O
90 2
Which nuclide is represented by X?
(1) 236Ra 92
(2) 228Ra 88
(3) 236U 92
re tested, ndicators, d thymol
n is
s neutral- . What is
Sample Regents Questions
49 After decaying for 48 hours, _1_ of the original 16
mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?
(1) 3.0 h (3) 12 h
(2) 9.6 h (4) 24 h
50 Which balanced equation represents nuclear
fusion?
(1) 21H 􏰀 21H → 42He
June 2013 #49
(4) 228U
88
is not -1 nuclei n nuclei
(3) 63Li 􏰀 10n → 31H 􏰀 42He (4) CaO 􏰀 CO → CaACnOswer
23
Choice #3
Explanation: Let’s figure out how many half-lives occurred to get to of the original mass.
1 X 2 = 2 = 1 : 1 half-life 16 16 8
81 X 2 = 28 = 41 : 2 half-lives
1 X 2 = 2 = 1 : 3 half-lives 4 4 2
21 X 2 = 2 = 1 : 4 half-lives
This sample underwent 4 half-lives in 48 hours.
48 = 12 4
One half-life is 12 hours.
497 © UNIT 12: NUCLEAR CHEMISTRY