The unstable isotope 234Th decays by ? emission with a half-life of 24.5 days
The initial decay rate of the sample was 9.9 × 1013 Bq. (1 u = 1.6605 x 10-27 kg)
(a) What mass of 234Th was initially present?
(b) What is the decay rate after 68 days?
(a) 0.12 g (b) 1.4 x 1013 Bq
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Planetary orbits are
a. parabolas. b. ellipses. c. circles. d. none of the above.
The binding energy per nucleon of a nucleus
A) increases steadily as we go to heavier elements. B) is approximately constant throughout the periodic table, except for very light nuclei. C) has a maximum near iron in the periodic table and decreases after that for heavier elements. D) decreases steadily as we go to heavier elements. E) has a minimum near iron in the periodic table and increases after that for heavier elements.
Stars swell into giants when hydrogen is exhausted in their centers
Indicate whether the statement is true or false
Inelastic Collisions: In an inelastic collision involving an isolated system, the final total momentum is
A. exactly the same as the initial momentum. B. more than the initial momentum. C. less than the initial momentum.