A sample originally contaived $10^{20}$ radioactive atoms, which emit $\alpha -$ particles. The ratio of $\alpha -$ particles emitted in the third year to that emitted during the second year is $0.3.$ How many $\alpha -$ particles were emitted in the first year?

  • [AIEEE 2012]
  • A

    $3\times 10^{18}$

  • B

    $7\times 10^{19}$

  • C

    $5\times 10^{18}$

  • D

    $3\times 10^{19}$

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