# Basic Physics of Nuclear Medicine/The Radioactive Decay Law MCQ

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1. 1 MBq is equal to:

1 billion decays per second | |||||||||||||

37 thousand, million curies | |||||||||||||

1 decay per second | |||||||||||||

1 million decays per second | |||||||||||||

→ | Correct Answer - see Units of Radioactivity. |

2. The Half Life of 99m-Tc is 6 hours. After how much time will one eighth of the radioactivity in a sample remain?

6 hours | |||||||||||||

12 hours | |||||||||||||

18 hours | |||||||||||||

→ | Correct Answer - see Half Life. | ||||||||||||

24 hours |

3. The Half Life is:

the reciprocal of the Decay Constant | |||||||||||||

the time taken for the number of radioactive nuclei to decrease by a factor of 2 | |||||||||||||

→ | Correct Answer - see Half Life. | ||||||||||||

the time taken for the number of radioactive nuclei to increase by a factor of 2 | |||||||||||||

the Decay Constant multiplied by the natural logarithm of 2 |

4. The Decay Constant is a measure of:

only the number of alpha particles emitted | |||||||||||||

only the number of beta particles emitted | |||||||||||||

only the number of gamma rays emitted | |||||||||||||

none of the above | |||||||||||||

→ | Correct Answer - see The Radioactive Decay Law. |

5. If ln x = y, then:

ln y = x | |||||||||||||

exp y = x | |||||||||||||

→ | Correct Answer - see The Radioactive Decay Law. | ||||||||||||

exp y = -x | |||||||||||||

exp -y = x |

6. When the Half Life increases:

the Decay Constant increases | |||||||||||||

the Decay Constant decreases | |||||||||||||

→ | Correct Answer - see Relationship between the Decay Constant and the Half Life. | ||||||||||||

the Decay Constant remains unchanged | |||||||||||||

none of the above happen |

7. A linear relationship is obtained between the number of radioactive nuclei and time when it is plotted:

on a log-log graph | |||||||||||||

on a log-linear graph | |||||||||||||

→ | Correct Answer - see The Radioactive Decay Law. | ||||||||||||

on a linear-linear graph | |||||||||||||

on a square-linear graph |

8. The number of nuclei which decay between t and t+dt is proportional to:

the number of nuclei only | |||||||||||||

the time interval only | |||||||||||||

the quotient of the number of nuclei and the time interval | |||||||||||||

the product of the number of nuclei and the time interval | |||||||||||||

→ | Correct Answer - see The Radioactive Decay Law. |

9. The Radioactive Decay Law is expressed by:

an exponential function | |||||||||||||

→ | Correct Answer - see The Radioactive Decay Law. | ||||||||||||

a logarithmic function | |||||||||||||

a sinusoidal function | |||||||||||||

a linear function |

10. When the Decay Constant increases:

the Half Life decreases | |||||||||||||

→ | Correct Answer - see Relationship between the Decay Constant and the Half Life. | ||||||||||||

the Half Life increases | |||||||||||||

the Half Life remains unchanged | |||||||||||||

none of the above happen |