A radioactive substance has an average life of 5 hours. In a time of 5 hours 

Which of the following radiations has the least wavelength

A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is 

Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called 

A radioactive decay chain starts from ${}_{93}{}^{237}\mathrm{Np}$ and produces ${}_{90}{}^{229}\mathrm{Th}$ by successive emissions. The emitted particles can be 

The half-life of a sample of a radioactive substance is 1 hour. If $8\times {10}^{10}$ atoms are present at t = 0, then the number of atoms decayed in the duration t = 2 hour to t = 4 hour will be

Carbon dating is best suited for determining the age of fossils if their age in years is of the order of 

A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is

The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant 

A radioactive material has a half life of 10 days. What fraction of the material would remain after 30 days

Starting with a sample of pure ${}_{66}\mathrm{Cu}$, $\frac{7}{8}$ of it decays into Zn in 15 min. The corresponding half-life is 

A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in 

A nucleus of mass 218 amu in free state decays to emit an $\mathrm{\alpha }$-particle. Kinetic energy of the $\mathrm{\alpha }$-particle emitted is 6.7 MeV. The recoil energy (in MeV) of the daughter nucleus is

${\mathrm{C}}^{14}$ has half life 5700 years. At the end of 11400 years, the actual amount left is  

Mean life of a radioactive sample is 100 seconds. Then its half life (in minutes) is

${}_{86}{}^{222}\mathrm{A}\to {}_{84}{}^{210}\mathrm{B}$. In this reaction how many $\mathrm{\alpha }$ and $\mathrm{\beta }$ particles are emitted 
(a) 6$\mathrm{\alpha }$, 3$\mathrm{\beta }$          (b) 3$\mathrm{\alpha }$, 4$\mathrm{\beta }$ 
(c) 4$\mathrm{\alpha }$, 3$\mathrm{\beta }$          (d) 3$\mathrm{\alpha }$, 6$\mathrm{\beta }$  

The phenomenon of radioactivity is 

If half life of radium is 77 days. Its decay constant in day will be

Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova explosion 5 billion years ago. The other was created in a nuclear reactor 5 minutes ago. The probability of decay during the next time is 

An $\mathrm{\alpha }$-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at a scattering angle of 180^o. The nearest distance up to which $\mathrm{\alpha }$-particle reaches the nucleus will be of the order of:

A neutron with velocity V strikes a stationary deuterium atom. Its kinetic energy changes by a factor of 

The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 $\mathrm{kilowatt}/{\mathrm{m}}^2$.The average earth- sun distance is $1.5\times {10}^{11}$ metres. The mass lost by the sun per day is
(1 day = 86400 seconds) 
(a) $4.4\times {10}^9 \mathrm{kg}$          (b) $7.6\times {10}^{14} \mathrm{kg}$
(c) $3.8\times {10}^{12} \mathrm{kg}$         (d) $3.8\times {10}^{14} \mathrm{kg}$

The binding energy per nucleon of ${\mathrm{O}}^{16}$ is 7.97 MeV and that of ${\mathrm{O}}^{17}$ is 7.75 MeV. The energy (in MeV) required to remove a neutron from ${\mathrm{O}}^{17}$ is 

The rest energy of an electron is 0.511 MeV. The electron is accelerated from rest to a velocity 0.5 c. The change in its energy will be

For uranium nucleus how does its mass vary with volume

In the nuclear fusion reaction ${}_1{}^2\mathrm{H}+{}_1{}^3\mathrm{H}\to {}_2{}^4\mathrm{He}+\mathrm{n}$ given that the repulsive potential energy between the two nuclei is $-7.7\times {10}^{-14} \mathrm{J}$, the temperature at which the gases must be heated to initiate the reaction is nearly
[Boltzmann’s constant $\mathrm{k}=1.38\times {10}^{-23} \mathrm{J}/\mathrm{K}$)
(a)${10}^9 \mathrm{K}$            (b) ${10}^7 \mathrm{K}$
(c) ${10}^5 \mathrm{K}$           (d)  ${10}^3 \mathrm{K}$

A nucleus with mass number 220 initially at rest emits an $\mathrm{\alpha }$-particle. If the Q value of the reaction is 5.5 MeV, calculate the kinetic energy of the $\mathrm{\alpha }$-particle

The half life of radioactive Radon is 3.8 days. The time at the end of which 1/20 th of the Radon sample will remain undecayed is
(Given ${\log }_{10}\mathrm{e}=0.4343$) 

If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately

A radioactive isotope X with a half-life of $1.37\times {10}^9$ years decays to Y which is stable. A sample of rock from the moon was found to contain both the elements X and Y which were in the ratio of 1 : 7. The age of the rock is