A radioactive source emits $2.4 - \mathrm { MeV }$ neutrons at the rate of 7100 neutrons per second. The number of atoms in the source is $2.6 \times 10 ^ { 9 }$. What is the activity of the source, in curies (Ci)? $( 1.00 \mathrm { Ci } = 3.70 \times$ $10 ^ { 10 } \mathrm {~Bq}$ )

Question

Quizplus · Accepted Answer

The activity of a radioactive source is defined as the rate at which the radioactive atoms decay, measured in decays per second or Becquerels (Bq). Given that the source emits 7100 neutrons per second, this directly indicates its activity is 7100 Bq. To convert this to curies (Ci), we use the conversion factor $1.00 \mathrm{Ci} = 3.70 \times 10^{10} \mathrm{Bq}$. Thus, the activity in curies is $7100 \mathrm{Bq} \times \frac{1 \mathrm{Ci}}{3.70 \times 10^{10} \mathrm{Bq}} = 1.92 \times 10^{-7} \mathrm{Ci}$, or $192 \mathrm{nCi}$, rounding to two significant figures gives $190 \mathrm{nCi}$.

A Radioactive Source Emits 2.4−MeV2.4 - \mathrm { MeV }2.4−MeV Neutrons at the Rate of 7100 Neutrons Per Second

A Radioactive Source Emits $2.4 - \mathrm { MeV }$ Neutrons at the Rate of 7100 Neutrons Per Second