Question

In a given sample there are 10,000 radio-active atoms of half-life period 1 month. The number of atoms remaining without disintegration at the end of 3 months is :

• A. Can't be calculated
• B. 5,000
• C. 2,500
• D. 1,250

Answer 1

Answer:

D. 1,250

• Half life is the time required for a quantity to reduce to half its initial value.
• Half-life period of the given sample = 1 month
• That is, the total time required for the sample to be half its present amount is 1 month.

• Given in the question, 10000 radio-active atoms are present in the given sample.
• These 10,000 radio-active atoms halve to 5000 atoms in 1 month.
• These 5000 radio-active atoms halve to 2500 atoms in 2 months.
• These 2500 radio-active atoms halve to 1250 atoms in 3 months.