If originally there were X atoms of radioactive isotope present and now there are only X/8 atoms, how many half-lives have elapsed?
A) 3
B) 1
C) 4
D) 2
A
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A grinding wheel is spinning at a rate of 20.0 revolutions per second. When the power to the grinder is turned off, the grinding wheel slows with constant angular acceleration and takes 80.0 s to come to a rest
(a) What was the angular acceleration of the grinding wheel as it came to rest? (b) How many rotations did the wheel make during the time it was coming to rest?
Hydrogen is generally classified as a
a. semimetal. b. nonmetal. c. metal. d. noble gas.
Baryons are composed of _______ quarks, and mesons are composed of ________ quarks
a. two, two c. three, three b. two, three d. three, two
For large mass number nuclei which are stable, the ratio of protons to neutrons is
a. equal to 1 b. greater than 1 c. less than 1 d. unrelated to the stability of nuclei e. almost 2 to 1