Quiz 2 (20 pts)
Chemistry 151 – Price
Name __________________________
Lab Section (circle) Wed Thurs __
1. (4 points) Explain the following statement: The smallest particles unique to an element
may be atoms or molecules.
2. (12 points) Argon has three naturally occurring isotopes 36Ar, 38Ar, and 40Ar. What is
the mass number of each? How many protons, neutrons and electrons are present in
each?
Mass
Protons
Neutrons
Electrons
Number
36Ar
38Ar
40Ar
3. (4 points) A laboratory instructor gives a sample of amino-acid powder to each of four
students, I, II, III, IV, and they weigh the samples. The true value is 8.72 g. Their
results for the three trials are:
I
II
III
IV
8.72g, 8.74g, 8.70g
8.56g, 8.77g, 8.83g
8.50g, 8.48g, 8.51g
8.41g, 8.72g, 8.55g
(a) Which student’s data set is the most accurate?
(b) Which student’s data set is the most precise?