Three $\mathrm{\alpha }$-particles and one $\mathrm{\beta }$-particle decaying takes place in series from an isotope ${}_{88}{}^{236}\mathrm{Ra}$. Finally the isotope obtained will be 

Half life of a radioactive substance is T. The time taken for all the nuclei to disintegrate will be

The half life of polonium is 140 days. After how many days, 16 gm polonium will be reduced to 1 gm (or 15g will decay) 

A radioactive element emits 200 particles per second. After three hours 25 particles per second are emitted. The half life period of element will be

The half life of the isotope ${}_{11}{}^{24}\mathrm{Na}$ is 15 hrs. How much time does it take for $\frac{7}{8}\mathrm{th}$ of a sample of this isotope to decay

If the half life of a radioactive sample is 10 hours,
its mean life is 

If 20 gm of a radioactive substance due to radioactive decay reduces to 10 gm in 4 minutes, then in what time 80 gm of the same substance will reduce to 10 gm 

16 gm sample of a radioactive element is taken from Bombay to Delhi in 2 hour and it was found that 1 gm of the element remained (undisintegrated). Half life of the element is 

Unit of radioactivity is Rutherford. Its value is

A radioactive substance has a half life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be

An element used for radioactive carbon dating for more than 5600 years is 

N atoms of a radioactive element emit n alpha particles per second. The half life of the element is

The radioactive nucleus ${}_7{}^{13}\mathrm{N}$ decays to ${}_6{}^{13}\mathrm{C}$ through the emission of 

The radioactive decay of uranium into thorium is expressed by the equation ${}_{92}{}^{238}\mathrm{U}\to {}_{90}{}^{234}\mathrm{Th}+\mathrm{X}$ where 'X' is

In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following would be emitted in the decay process 

The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be

In the uranium radioactive series, the initial nucleus is ${}_{92}{}^{238}\mathrm{U}$ and the final nucleus is ${}_{82}{}^{206}\mathrm{Pb}$. When the uranium nucleus decays to lead, the number of  $\mathrm{\alpha }$-particles emitted will be 

Which of the following is a correct statement

The half life of ${}_{131}\mathrm{I}$ is 8 days. Given a sample of ${}_{131}\mathrm{I}$ at time t = 0, we can assert that 

Carbon-14 decays with half-life of about 5,800 years. In a sample of bone, the ratio of carbon-14 to carbon-12 is found to be $\frac{1}{4}$ of what it is in free air. This bone may belong to a period about x centuries ago, where x is nearest to 

In the disintegration series ${}_{92}{}^{238}\mathrm{U}\stackrel{\mathrm{\alpha }}{\to }\mathrm{X}\stackrel{\mathrm{\beta }-}{\to }{}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{Y}$ the values of Z and A respectively will be 

The particles emitted by radioactive decay are deflected by magnetic field. The particles will be

Half life of a radioactive element is 10 days. The time during which quantity remains 1/10 of initial mass will be

In the given nuclear reaction A, B, C, D, E represents
${}_{92}{}^{238}\mathrm{U}\stackrel{\mathrm{\alpha }}{\to }{}_{\mathrm{B}}{}^{\mathrm{A}}\mathrm{Th}\stackrel{\mathrm{\beta }}{\to }{}_{\mathrm{D}}{}^{\mathrm{C}}\mathrm{Pa}\stackrel{\mathrm{E}}{\to }{}_{92}{}^{234}\mathrm{U}$

If half life of a radioactive element is 3 hours, after 9 hours its activity becomes 

At any instant the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances?

Which of the following isotopes is used for the treatment of cancer 

If half-life of a radioactive atom is 2.3 days, then its decay constant would be 

A radio isotope has a half life of 75 years. The fraction of the atoms of this material that would decay in 150 years will be

An artificial radioactive decay series begins with unstable ${}_{94}{}^{241}\mathrm{Pu}$. The stable nuclide obtained after eight α decays and five $\mathrm{\beta }$-decays is