A radioactive sample decays by two modes by $\alpha $ decay and by $\beta -decay$. $66.6 \%$ of times it decays by $\alpha -decay$ and $33.3 \%$ of times, it decays by $\beta -decay$. If half life of sample is $60$ years then what will be half life of sample, if it decays only by $\alpha - decay$. ............ $years$
$30$
$90$
$120$
$180$
$99\%$ of a radioactive element will decay between
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 |
The half life of polonium is $140\, days$. After how many days, $16 \,gm$ polonium will be reduced to $1 \,gm$ .........$days$(or $15\,g$ will decay)
A certain radioactive nuclide of mass number $m_x$ disintegrates, with the emission of an electron and $\gamma$ radiation only, to give second nuclied of mass number $m_y.$ Which one of the following equation correctly relates $m_x$ and $m_y$ ?
The rate of disintegration of a fixed quantity of a radioactive element can be increased by