Chemistry Unit 4 Test Review

An unstable nucleus __________.

• Increases its nuclear mass through fission.

• Expels all of its neutrons.

• Increases its half-life.

• Emits energy when it decays.

What does the number 235 represent in Uranium-235

• The atomic number

• The number of neutrons

• The mass number

• The mass defect

What is the charge on a gamma ray?

• -1

• +1

• 0

• +2

What particle is emitted in an alpha decay equation?

• Helium nucleus

• Positron

• Electron

• Proton

A beta particle is a(n)...

• Helium nucleus

• Proton

• Neutron

• Electron

What is the least penetrating form of radiation?

• Beta radiation

• Alpha radiation

• Gamma radiation

What is the most penetrating form of radiation?

• Alpha radiation

• Beta radiation

• Gamma radiation

The half-life for gold-198 is 2.69 days. An original sample of gold-198 has a mass of 10.0 g. How much of this sample will remain after 10.76 days?

• 2.50 g

• 0.625 g

• 160. g

• 40.0 g

The half-life of sodium-24 is 15 hours. How much sodium-24 will remain after 3.75 days, if the initial sample was 20.0 grams?

• 2.50 g

• 1.25 g

• 0.313 g

• 80.0 g

Sodium-25 has a half-life of 1.00 minute. If 9.31 x 10^-7 g remains after 30.0 minutes, what was the mass of the original sample?

• 1250 g

• 1000 g

• 250. g

• 750. g