Nuclide Notation and Half-life

A radioactive substance has a half-life of 2 weeks. At the beginning of an investigation, a sample of the substance emits 3000 β-particles per minute.

How many β-particles will it emit per minute after 6 weeks?

• 0

• 375

• 500

• 1500

Tags

NGSS.HS-PS1-8

A nuclide has the symbol shown.
How many protons are there in one nucleus of this nuclide?

• 6

• 8

• 14

• 20

Tags

NGSS.HS-PS1-8

39. A radioactive substance emits radiation at a rate of 600 emissions per second. Four hours later, it emits radiation at a rate of 300 emissions per second.
    What is the half-life of the substance and what is the rate of emission after a further four hours?

• half-life - 2 hours

  rate after a further 4 hours - 0

• half-life - 2 hours

  rate after a further 4 hours - 150

• half-life - 4 hours

  rate after a further 4 hours - 0

• half-life - 4 hours

  rate after a further 4 hours - 150

Tags

NGSS.HS-PS1-8

The nuclide notation for an isotope of silver is shown.

How many nucleons are in a nucleus of this isotope?

• 47

• 62

• 109

• 156

Tags

NGSS.HS-PS1-8

The graph shows the percentage of a radioactive isotope that remains as time passes.

A student measures the initial rate of emission of this isotope as 40 000 emissions per second. How long does it take for the rate of emission to fall to 5000 emissions per second?

• 5 minutes

• 15 minutes

• 20 minutes

• 40 minutes

Tags

NGSS.HS-PS1-8

38. What are isotopes of an element?

• 1. atoms of a different element with a different number of neutrons

• 1. atoms of a different element with a different number of protons

• 1. atoms of the same element with a different number of neutrons

• 1. atoms of the same element with a different number of protons

Tags

NGSS.HS-PS1-8

The graph shows the count rate from a radioactive source over a period of time.

What is the half-life of the source?

• 0.5 hour

• 1.0 hour

• 1.5 hours

• 3.0 hours

Tags

NGSS.HS-PS1-8

Three students are describing the structure of an atom.

student 1 All the positively charged particles are in the nucleus.

student 2 Positive electrons are in the nucleus.
student 3 Negative electrons orbit around the nucleus.

Which students are making a correct statement?

• 1, 2 and 3

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Tags

NGSS.MS-PS1-1

The graph shows how the count rate from a radioactive sample changes with time.

What is the half-life for this sample?

• 90s

• 120s

• 200s

• 400s

Tags

NGSS.HS-PS1-8

37. A sample of americium decays and changes into neptunium. The half-life of americium is 432 years.

    Which fraction of the americium will remain after 1728 years?

• 0

Tags

NGSS.HS-PS1-8