Isotopes and Radioactive Decay

When an unstable radioactive atom decays, it usually turns into:

• a more stable atom
• a less stable atom
• the exact same atom but with less pure energy
• empty space

Tags

NGSS.HS-PS1-8

Radiometric dating is possible because the rates of decay of radioactive isotopes _____.

• change over time
• change from place to place
• are constant
• vary widely

Tags

NGSS.HS-PS1-8

The time it takes for 50% of the nuclei in a radioactive sample to decay to its stable isotope is called _____.

• the daughter product
• geologic time
• the half-life
• the half-time

Tags

NGSS.HS-PS1-8

You find a rock sample with radioactive atoms present.  If 12.5% of the original radioactive atoms were present, how many half-lives has the rock been around for? (Hint, at Half-Life = 0, you start with 100%)

• zero
• 1
• 2
• 3

Tags

NGSS.HS-PS1-8

You find a rock sample with radioactive atoms present.  If 25% of the original radioactive atoms were present, how many half-lives has the rock been around for? (Hint, at Half-Life = 0, you start with 100%)

• zero
• 1
• 2
• 3

Tags

NGSS.HS-PS1-8

If the half-life of a radioactive group of atoms is 100 years, then how old is the rock if there have been two half-lives?

• 25 years
• 200 years
• 400 years
• 800 years

Tags

NGSS.HS-PS1-8

The table shows the radioactive decay of carbon-14. Part of the table has been left blank. 
After 22,800 years, approximately what percentage of the original carbon-14 remains? 

• 15%
• 12.5%
• 6.25%
• 3.125%

Tags

NGSS.HS-PS1-8

An isotope of silver has a half-life of 10 minutes. What fraction of the original mass would remain after one hour?

• 1/64

• 1/2

• 1/4

• 1/8

Tags

NGSS.HS-PS1-8

Isotopes are atoms of the same element with different #’s of __________ & therefore different __________.

• n⁰ ;  atomic #’s
• p⁺ ; atomic #’s
• e^- ; atomic masses
• n⁰ ; atomic masses

Tags

NGSS.HS-PS1-8

How many neutrons does the isotope below have?     ⁸⁹ ₃₆Kr

• 53
• 36
• 89
• 125

Tags

NGSS.HS-PS1-8