The nuclide  $\frac{214}{82}$  Pb emits an electron and becomes nuclide X. Which of the following gives the mass number and atomic number of nuclide X?

• Mass # = 210  Atomic # = 80

• Mass # = 213  Atomic # = 83

• Mass # = 214  Atomic # = 81

• Mass # = 214  Atomic # = 83

The additional product of the nuclear fission reaction shown above is

• $\frac{91}{36}$ Kr

• $\frac{92}{35}$ Br

• $\frac{93}{36}$ Kr

• $\frac{93}{37}$ Rb

Cobalt 60 is a radioactive source with a half-life of about 5 years. After how many years will the activity of a new sample of cobalt 60 be decreased to 1/8 its original value?

• It depends on the original amount of cobalt 60.

• 5 years

• 2.5 years

• 10 years

• 15 years

The graph above shows the decay of a sample of carbon 14 that initially contained N_o atoms. Which of the lettered points on the time axis could represent the half-life of carbon 14 ?

• A

• B

• C

• D

• E

A nuclear reactor uses uranium-235 to produce energy. What is the order of magnitude of the energy equivalent of 6 x 10^-4 kg of uranium 235 ?

• 10⁵ J

• 10⁸ J

• 10¹⁴ J

• 10¹⁷ J

• 10²⁰ J

In the decay represented above, what is the nucleon number of particle X?

• 82

• 83

• 213

• 214

A typical iron nucleus contains 30 neutrons and 26 protons. Which of the following explains why the nucleus stays together despite the electric repulsion between the protons?

• The net gravitational force exerted on each proton due to all the nucleons is stronger than the net repulsive force.

• The neutrons become polarized and exert a net attractive electric force on each proton that is stronger than the net repulsive force.

• The net magnetic force exerted on each proton due to all the nucleons is stronger than the net repulsive force.

• The net strong force on each proton due to all the nucleons is stronger than the net repulsive force.

A radioactive oxygen  $\frac{15}{8}$  O nucleus emits a positron and becomes

•  $\frac{15}{7}$  N 

•  $\frac{14}{9}$  F

•  $\frac{15}{8}$  O

•  $\frac{15}{9}$  F