A sample of strontium-90 has an activity of 5000 Bq. After 120 years the activity has fallen to 625 Bq. What is the half life of strontium-90?

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  the unit of the measure =

explanation:

  the property that is quantified by the energy needed per of material to raise the temperature by one.

  si unit of energy = joule (j)

  si unit of temperature = kelvin (k)

  si unit of mass of material = kilogram (kg)

the property that is quantified by the energy needed per of material to raise the temperature by one is called specific heat.

the unit of specific heat is

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