Half life of radioactive element depends upon

A radioactive sample has half-life of $5$ years. Probability of decay in $10$ years will be  ……..$\%$

The nucleus $_{10}^{23} Ne$ decays by $\beta^{-}$ emission. Write down the $\beta$ -decay equation and determine the maximum kinetic energy of the electrons emitted. Given that

$m\left(_{10}^{23} Ne \right)=22.994466 \;u$

$m\left(_{11}^{23} Na\right) =22.089770\; u$

Which of the following statements are true regarding radioactivity

$(I)$ All radioactive elements decay exponentially with time

$(II)$ Half life time of a radioactive element is time required for one half of the radioactive atoms to disintegrate

$(III)$ Age of earth can be determined with the help of radioactive dating

$(IV)$ Half life time of a radioactive element is $50\%$ of its average life periodSelect correct answer using the codes given belowCodes :

The rate of radioactive disintegration at an instant for a radioactive sample of half life $2.2 \times 10^9 \;s$ is $10^{10}\; s ^{-1}$. The number of radioactive atoms in that sample at that instant is,