A piece of wood from a recently cut tree shows $20\,decays$ per minute. A wooden piece of same size placed in a museum ( obtained from a tree cut many years back) shows $2\,decays$ per minute. If half life of $C^{14}$ is $5730\, years$, then age of the wooden piece placed in the museum is approximately ........... $years$
$10439$
$13094$
$19039$
$39049$
Match the nuclear processes given in column $I$ with the appropriate option$(s)$ in column $II$
column $I$ | column $II$ |
$(A.)$Nuclear fusion | $(P.)$ Absorption of thermal neutrons by ${ }_{92}^{213} U$ |
$(B.)$Fission in a nuclear reactor | $(Q.)$ ${ }_{27}^{60} Co$ nucleus |
$(C.)$ $\beta$-decay | $(R.)$ Energy production in stars via hydrogen conversion to helium |
$(D.)$ $\gamma$-ray emission | $(S.)$ Heavy water |
$(T.)$ Neutrino emission |
A radio-isotope has a half- life of $5$ years. The fraction of the atoms of this material that would decay in $15$ years will be
Substance $A$ has atomic mass number $16$ and half life of $1$ day. Another substance $B$ has atomic mass number $32$ and half life of $\frac{1}{2}$ day. If both $A$ and $B$ simultaneously start undergo radio activity at the same time with initial mass $320\,g$ each, how many total atoms of $A$ and $B$ combined would be left after $2$ days $.........\times 10^{24}$
A ${\pi ^0}$ at rest decays into $2\gamma $ rays ${\pi ^0} \to \gamma + \gamma $. Then which of the following can happen
A freshly prepared radioactive source of half life $2$ hours $30$ minutes emits radiation which is $64$ times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be hours.