Nuclear physics

Question

A sample originally contained 10²⁰ radioactive atoms, which emit α-particles. The ratio of α - particles emitted in the third year to that emitted during the second year is 0.3. How many α-particles were emitted in the first year?

A) 3× 10⁸

 B)3×10¹⁹

^{C)3×10^20}

Answer 1

Let N₀ be initial amount of atom which is 10²⁰ and say λ is decay constant 
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We know,

 So, amount decayed in 1st year =7×10¹⁹