WorksheetsAPES UCLA MATH
Total questions: 10
Worksheet time: 19mins
Name
Class
Date
1.
An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?
a)
+25
b)
+30
c)
-25
d)
-30
2.
A transfer of energy involves three steps, each of which is 80% efficient. What is the approximate total efficiency of all three steps?
a)
66%
b)
51%
c)
24%
d)
80%
3.
A population takes about seven years to double in size. This population annual percentage growth is approximately
a)
2%
b)
7%
c)
10%
d)
15%
4.
A population experienced a birth rate of 23 people per thousand and a death rate of 11 deaths per thousand. What is the approximate growth rate of the population?
a)
2.4%
b)
1.2%
c)
3.8%
d)
0.12%
5.
. Radioactive I-131 has a half-life of 8 days. How much time is required for a millicurie sample of I-131 to decay to an activity of 1 microcurie?
a)
about 3 months
b)
about a year
c)
16 days
d)
about 1 month
6.
An adult takes 400 mg of ibuprofen. Each hour, the amount of ibuprofen in the person’s system decreases by about 20%. How much ibuprofen is left after 4 hours?
a)
205 mg
b)
256
c)
320 mg
d)
164mg
7.
What is Half-life?
a)
The amount of time it takes for some of the nuclei in a sample of the isotope to decay
b)
The amount of time it takes for half the electrons in a sample of the isotope to decay
c)
The amount of time it takes for half the nuclei in a sample of the isotope to decay
d)
the amount of time it takes to double the nuclei in a sample of the isotope to decay
8.
After the third half-life, how much of the sample is left?
a)
1/2
b)
1/3
c)
1/16
d)
1/8
9.
Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?
a)
0.25g
b)
2.5g
c)
25g
d)
80g
10.
How many protons does U 235 atom have ?
a)
235
b)
92
c)
143
d)
67
100 %
