Nuclear Chemistry and Half-Lifes

The time taken for half of an amount of radioactive atoms to decay.

• Nuclear fusion
• Full-life
• Dead time
• Half-life

Tags

NGSS.HS-PS1-8

Q1. How much would a 20 gram sample of sodium-24 be left after decaying 45 hours if the half-life of sodium is 15 hours?

• 2.5 grams

• 3 grams

• 6.7 grams

• 20 grams

Q2: How long would it take for a 100 gram sample of Ti-51 to decay so only 3.125 grams of radioactive material are left? The half-life of Ti-51 is 6 minutes.

• 6 minutes

• 24 minutes

• 30 minutes

• 60 minutes

Q3: If the patient is given a 2.0 gram sample of I-131 during therapy, how much I-131 remains in his body after 48.6 days, given the half-life of I-131 is 8.1 days?

• .03125 grams

• .0625 grams

• 1 gram

• 128 grams

Q4a: How much carbon-14 would be left if an original sample of C-14 (half-life is 5730 years) had a mass of 56 grams and 3 half-lifes had passed?

• 3 grams

• 7 grams

• 18.7 grams

• 716.25 grams

Q4b: How much time has passed if a sample of carbon-14 (half-life is 5730 years) had a mass of 56 grams and has undergone 3 half-lifes?

• 42 years

• 1910 years

• 5730 years

• 17190 years