types of radioactive decay

• • background radiation was tested for 10 min and recorded so counts we then tested rock A for 10 min and recorded 250 counts. What is the activity
• 1)counts from background radiation is 50
• 2) counts from rock A is 1250-50 = 1200
• 3) activity of rock a is 10min=600sec sp 1200/600 = 2Bq(activity)
• when you test activity of source measure and subtract background radiation counts