Half-life

What is the count rate after 45 days for a radioactive isotope with a half-life of 15 days and an initial count rate of 200 counts per second?

• 50 counts per second
• 100 counts per second
• 12.5 counts per second
• 25 counts per second

Tags

NGSS.HS-PS1-8

What does a decrease in count rate indicate?

• A slower rate of decay
• A doubling rate of decay
• A faster rate of decay
• A constant rate of decay

Tags

NGSS.HS-PS1-8

What is the count rate after 60 days for a radioactive isotope with a half-life of 20 days and an initial count rate of 1000 counts per second?

• 500 counts per second
• 250 counts per second
• 125 counts per second
• 62.5 counts per second

Tags

NGSS.HS-PS1-8

How is half-life defined?

• The time it takes for the number of nuclei to remain constant
• The time it takes for the number of nuclei to halve
• The time it takes for the number of nuclei to triple
• The time it takes for the number of nuclei to double

Tags

NGSS.HS-PS1-8

What is the relationship between the rate of decay and the length of the half-life?

• The rate of decay is directly proportional to the length of the half-life
• The rate of decay is unrelated to the length of the half-life
• The rate of decay is equal to the length of the half-life
• The rate of decay is inversely proportional to the length of the half-life

Tags

NGSS.HS-PS1-8

What is the relationship between decay and half-life?

• Decay is the process by which half-life occurs
• Decay is the process that determines the length of half-life
• Decay is unrelated to half-life
• Decay is the result of half-life

Tags

NGSS.HS-PS1-8

How can half-life be applied to solve problems related to radioactive isotopes?

• By analyzing the count rate
• By calculating the decrease in count rate
• By determining the decay rate
• By calculating the number of nuclei

Tags

NGSS.HS-PS1-8

How can you determine the half-life of an isotope from a graph?

• By counting the number of decays per second
• By measuring the time it takes for the number of nuclei to halve
• By measuring the time it takes for the number of nuclei to double
• By measuring the time it takes for the count rate to fall to half its initial level

Tags

NGSS.HS-PS1-8

What can half-life be used for?

• To determine the number of nuclei in a sample
• To predict when a nucleus will decay
• To solve problems related to radioactive isotopes
• To measure the rate of decay

Tags

NGSS.HS-PS1-8

What does a longer half-life indicate?

• A faster rate of decay
• A doubling rate of decay
• A slower rate of decay
• A constant rate of decay

Tags

NGSS.HS-PS1-8