Alpha rays emitted from a radioactive substance are
Negatively charged particles
Ionised hydrogen nuclei
Doubly ionised helium atom
Uncharged particles having the mass equal to proton
In the uranium radioactive series, the initial nucleus is $_{92}{U^{238}}$ and the final nucleus is $_{82}P{b^{206}}$. When the uranium nucleus decays to lead, the number of $\alpha - $ particles emitted will be
Half lives of two radioactive nuclei $A$ and $B$ are $10\, minutes$ and $20\, minutes$, respectively. If, initially a sample has equal number of nuclei, then after $60$ $minutes$ , the ratio of decayed numbers of nuclei $A$ and $B$ will be
Ten percent of a radioactive sample has decayed in $1$ day. After $2$ days, the decayed percentage of nuclei will be ...... $\%$
If half life of radium is $77$ days. Its decay constant in day will be
What is the half-life (in years) period of a radioactive material if its activity drops to $1 / 16^{\text {th }}$ of its initial value of $30$ years?