A freshly prepared radioactive sample has activity 10¹⁰ s⁻¹ and mean life 10⁹ s. The mass of one atom is 10⁻²⁵ kg. Find the sample mass in mg.
Physics · Nuclear physics
JEE Mains Advanced

Question

A freshly prepared radioactive sample has activity 10¹⁰ s⁻¹ and mean life 10⁹ s. The mass of one atom is 10⁻²⁵ kg. Find the sample mass in mg.

G1 Physics · Accepted Answer

A=λN=N/τ, so N=Aτ=10¹⁰×10⁹=10¹⁹ atoms. Mass =10¹⁹×10⁻²⁵ kg=10⁻⁶ kg=1 mg.