What is the half-life of Cobalt-57?

What is the half-life of Cobalt-57?

• A. 9 Months
• B. 9 Days
• C. 57 Days
• D. 1 Year

Answer: (A)

Half-life is the time it takes for half of a radioactive substance to decay. Cobalt-57 has a half-life of about 270 days, which is roughly nine months. That makes the “nine months” choice the best match, since the other times are much shorter or longer than cobalt-57’s actual decay time (days or a year don’t fit). This 9-month range is a characteristic property of this isotope and is useful for planning experiments and calibrations that rely on its activity level.

Half-life is the time it takes for half of a radioactive substance to decay. Cobalt-57 has a half-life of about 270 days, which is roughly nine months. That makes the “nine months” choice the best match, since the other times are much shorter or longer than cobalt-57’s actual decay time (days or a year don’t fit). This 9-month range is a characteristic property of this isotope and is useful for planning experiments and calibrations that rely on its activity level.