Unit 5 study guide problems

Without the sun, life on earth would not exist. There would be no warmth, no plants, no animals, no night and day.

To power itself, the sun is constantly generating a nuclear reaction in its core, in which hydrogen nuclei are combined to form helium. This process is known as ​ ​ ​ (a)  

• fusion
• fission
• alpha
• beta
• gamma
• half life

What is one way in which fission differs from fusion?

• Fission releases energy, fusion absorbs energy.

• Fission deals with the nucleus, fusion pertains to the electrons.

• Fission splits nuclei, fusion combines nuclei.

• Fission is not a radioactive process, fusion is radioactive.

This radioactive particle, emitted from carbon-14, has a negative charge. It contains sufficient energy to burn human skin and can pass through paper.

• alpha

• beta

• gamma

• half life

 Solve AND identify this radioactive decay equation

238 U -----> _____ + 234Th

92                            90

• 4 He

  2

  alpha

• 4 He

  2

  beta

• 0 e

  -1

  beta

• 0 e

  -1

  alpha

List the three types of radioactive decay from least harmful to most harmful that we discussed in class

• alpha, beta, gamma

• gamma, beta, alpha

• beta, alpha, gamma

• alpha

• beta

• gamma

• none

A radioactive substance decays with a half-life of 12,000 years. If the substance is stored for 36,000 years, then what fraction of it remains?

• 1/2

• 1/8

• 1/24

• 1/64

An isotope of cesium (cesium-137) has a half-life of 30 years. If 1.0 mg of cesium-137 disintegrates over a period of 90 years, how many mg of cesium-137 would remain?

• .5mg

• .25mg

• .125mg

• .0625mg

What is Half-life?

• The amount of time it takes for some of the nuclei in a sample of the isotope to decay

• The amount of time it takes for half the electrons in a sample of the isotope to decay

• The amount of time it takes for half the nuclei in a sample of the isotope to decay

• the amount of time it takes to double the nuclei in a sample of the isotope to decay

What is the half life of the nucleus?

• 5 sec

• 10 sec

• 15 sec

• 25 sec