The half-life of radon is 3.8 days. Three fourth Of a radon sample decay in
The binding energy per nucleon for C 12 is 7.68 MeV and that for C 13 is 7.47 MeV. The energy required to remove a neutron from C 13 is
Calculate the ground state Q value of the induced fission reaction in the equation n + 92 U 23 Z r 40 99 + T e 52 134 + 3 n m ( n ) = 1.0087 u ; M U 235 = 235.0439 u M ( Z r ) = 98.916 u ; M T e 134 = 133.9115 u
Two radio active nuclei x and y initially contain an equal no.of atoms. Their half life are 1 hr, 2 hrs. The ratio of their rates of disintegration after 2 hrs from the start is
Radioactive element decays to form a stable nuclide, then the rate of decay of reactant dN dt will vary with time (t) as shown in figure.
A radioactive sample has N 0 active atoms at t = 0. If the rate of disintegration at any time is R and the number of atoms is N, then the ratio R/N varies with time as
If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately
The half life of radium is 1620 years and its atomic weight is 226 kg per kilo mol. The number of atoms that will decay from its 1 gm sample per second will be
The rate of disintegration was observed to be 10 17 disintegrations per sec when its half life period is 1445 years. The original number of particles are
A radio active nucleus emits both α and β − particles. Initial mass number of the nucleus is 298. After emission of α and β − particles, the nucleus becomes an isotope and mass number becomes 274. Then number of β − particles emitted is
A nucleus disintegrates into two nuclear parts which have their velocities in ratio 2 : 1. The ratio of their nuclear sizes will be
A radioactive substance of half life T is produced at constant rate. The time after which its activity becomes half of the rate of production is
A nucleus with mass number 220 initially at rest emits an α -particle. If the Q-value of the reaction is 5.5 MeV, the kinetic energy of the α -particle is
To generate a power of 3.2megawatt, the number of fissions of U 235 per minute is (Energy released per fission=200MeV, 1eV= 1 .6 × 10 − 19 J )
The binding energy per nucleon of L 3 7 i and H 2 4 e Nuclei are 5.60 MeV and 7.06 MeV respectively. In the nuclear reaction Li 3 7 + H 1 1 He 2 4 + He 2 4 + Q the value of energy Q released is
A radioisotope X with a half life 1.4 × 10 9 years decays to Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 1: 7 . The age of the rock is
α -particle consists of
The rate of radioactive disintegration at an instant for a radioactive sample of half life 2 . 2 × 10 9 s is 10 10 s – 1 The number of radioactive atoms in that sample at that instant is,
A freshly prepared radio active source of half life 2 hr emits radiation of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is
There are two radioactive substances A and B. Decay constant of B is two times that of A. Initially, both have equal number of nuclei. After n half-lives of A, rates of disintegration of both are equal. The value of n is
The half life of a radio active substance is 2h. After 4 hr fractional change in activity will be
In which of the following processes, the number of protons in the nucleus increase ?
In the case of Thorium (A = 232 and z = 90), we obtain an isotope of Lead (A = 208 and z = 82) after some radio active disintegrations. The number of β particles emitted are respectively
The masses of neutron and proton are 1.0087amu and 1.0073 amu respectively. If the neutrons and protons combine to form helium nucleus of mass 4.0015 amu the binding energy of the helium nucleus will be
Nuclear forces are
One requires energy E n to remove a nucleon from a nucleus and an energy E e to remove an electron from the orbit of an atom. Then
The mass of an α -particle is
The radius of a nucleus of a mass number A is directly proportional to
The force acting between proton and proton inside the nucleus is
Radius of He 2 4 nucleus is 3 Fermi. The radius of Pb 82 206 nucleus will be
1 g of hydrogen is converted into 0.993 g of helium in a thermonuclear reaction. The energy released is
γ – rays radiation can be used to create electron-positron pair. In this process of pair production, γ – rays energy cannot be less than
A radioactive sample whose half-life is 40h has 18 times more activity than required for safety, then after how many half-lives will the radioactive sample will be safe?
The binding energy per nucleon is maximum in the case of
A nucleus of Po 84 210 originally at rest emits α – particle with speed v. What will be the recoil speed of the daughter nucleus?
The binding energy per nucleon E Vs nuclear mass (M) for different nuclei is given below. In which case energy is released?
99% of a radioactive element will decay between
The half-life of a sample of a radioactive substance is 1 hour.If 8 x 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
The binding energy per nucleon of O 16 is 7 . 97 MeV and that of O 17 is 7 . 75 MeV . The energy (in MeV) required to remove a neutron from O 17 is
A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio 8 : 1. The ratio of radii of the fragments is
The half life period of a radioactive element X is same as the mean life time of another radioactive element Y. Initially both of them have the same number of atoms. Then
For a substance the average life for α – emission is 1620 years and for β -emission is 405 years. After how much time the 1/4 of the material remains after α and β emission?
A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is 0.5 MeV and the total kinetic energy of the electron-positron pair is 0.78 MeV, then the energy of the gamma ray photon must be
Given mass number of gold = 197, density of gold = 19.7g cm –3 , Avogadro’s number = 6 × 10 23 . The radius of the gold atom is approximately.
Plutonium decays with a half-life of 24,000 years. If plutonium is stored for 72,000 years, what fraction of it remains ?
In moon rock sample the ratio of the number of stable argon-40 atoms present to the number of radioactive potassium-40 atoms is 7:1. Assume that all the argon atoms were produced by the decay of potassium atoms, with a half-life of 2.5 × 10 9 yr. The age of the rock is
The mass defect for the nucleus of Helium is 0.0303 amu. The binding energy per nucleon in MeV is nearly
Alpha particle decay is possible if
As a result of radioactive decay a 92 U 238 nucleus is changed to a 91 U 234 nucleus. Which particles are emitted in the decay?
What fraction of initial number of active nuclei is decayed between t = 2T and t = 4T, where T = half life?
The time elapsed between 25% and 50% decay of a radioactive sample having half life of 1 hour is
Th6 intensity of γ radiation from a given source is I. On passing through 36 mm of lead, it is reduced to I / 8. The thickness of lead, which will reduced the intensity to I/ 2will be
A radioactive nucleus undergoes a series of decay according to the scheme A ⟶ α A 1 ⟶ β − A 2 ⟶ α A 3 ⟶ γ A 4 If the mass number and atomic number of A are 180 and 72 respectively, what are these numbers for A 4 ?
Fusion reaction takes place at high temperature because
Half – life of a radioactive substance is 20min. The time between 20% and 80% decay will be
Which of the following atoms has the lowest ionization potential?
After a time t has elapsed, 90% of a radioactive sample is undecayed. The percent that will decay in a time 2t is
For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is
In a certain nuclear reactor, a radioactive nucleus is being produced at a constant rate =1000/s. The mean life of the radionuclide is 40 minutes. At steady state the number of radionuclide will be
The binding energy per nucleon of O 16 is 7.97 MeV and that of O 17 is 7.75 MeV. The energy (in MeV) required to remove a neutron from O 17 is
The fission of U 235 can be triggered by the absorption of a slow neutrons by a nucleus. Similarly, a slow proton cannot also be used. This statement is
There are two radioactive substances A and B. Decay constant of B is two times that of A. Initially, both have equal number of nuclei. After n half lives of A, rate of disintegration of both are equal. The value of n is
A nucleus of uranium decays at rest into nuclei of thorium and helium. Then
A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is (given 1 u = 931 MeV)
The half life of a radioactive isotope ‘X’ is 20 years. It decays to another element ‘Y’ which is stable. The two elements ‘X’ and ‘Y’ were found to be in the ratio 1 : 7 in a sample of a given rock. The age of the rock is estimated to be
If radius of the Al 13 27 nucleus is taken to be R Al , then the radius of Te 53 125 nucleus is nearly
The ratio of the radii of the nuclei 13 A l 27 a n d 54 T e 125 i s
Activity of a radioactive element decreased to one-third of original activity I 0 in 9 yr. After further 9 yr, its activity will be
How does the Binding Energy per nucleon vary with the increase in the number of nucleons?
The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is
α -particles, β -particles and γ -rays are all having same energy. Their penetrating power in a given medium in increasing order will be
When Radio – active element is heated. It’s activity
Half – life period of a Radioactive element X is same as the mean – life time of another radio active element Y. If initially both have same number of atoms then
If the rest mass of electron or positron is 0.51 MeV, then the kinetic energy of each particle in the electron-positron pair production by a -photon of 2.42 MeV will be
Radioactive material ‘A’ has decay constant ‘8 λ ‘ and material ‘B’ has decay constant ‘ λ ‘. Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material ‘B’ to that ‘A will be e ?
The half life of a radioactive sample undergoing α – decay is 1 . 4 × 10 17 s. If the number of nuclei in the sample is 2 . 0 × 10 21 ,the activity of the sample is nearly
The E.M. wave with shortest wavelength among the following is,
The energy equivalent of 0.5g of a substance is
What happens to the mass number and atomic number of an element when it emits γ -radiation?
The graph between number of decayed atom N 1 of a radioactive element and time ‘t’ is
The ratio of the radii of the nuclei 13 A l 27 and 54 T e 125 is
There are two radioactive substance A & B, Decay constant of B is two times that of A. initially, both have equal number of nuclei. After n half lives of A, rate of disintegration of both are equal. The value of ‘h’ is
A heavy nucleus having mass number 200 gets disintegrated into two small fragments of mass number 80 and 120. If binding energy per nucleon for parent atom is 6.5 MeV and for daughter nuclei is 7 MeV and 8 MeV respectively, then the energy released in the decay will be:
A radioactive sample undergoes decay as per the following graph. At time t = 0 , the number of undecayed nuclei is N 0 . Calculate the number of nuclei left after 10s. g i v e n log e ( 2 ) = 0 . 693
The energy liberated per nuclear fission is 200 MeV. If 10 20 fissions occur per second the amount of power produced will be :
In the nuclear process 6 C 11 B 11 5 +e + + x, X stands for
The activity of a radio active sample decreases to one third of its original value in 9 years, what will be the activity after further 9 years?
How much energy must be imparted to the proton so as to start the reaction 3 Li 7 + H 1 1 Be 7 4 + n 1 0 ( Given that mass of 3 Li 7 = 7 . 016 amu , H 1 1 = 1 . 00783 amu , Be 7 4 = 7 .01693 amu and n 1 0 = 1 .00866 amu , 1 amu = 931 .5 MeV / C 2 )
What should be the activity of a radio active sample of mass ‘m’ and decay constant λ , after time t ? (Take molecular mass of sample be M and Avogardro’s number be N a ).
There are three lumps of a given active substance. Their activities are in the ratio of 1 : 2 : 3 now. What will be the ratio of their activities at any further date?
The binding energies per nucleon are 5.3 MeV, 6.2 MeV and 7.4 MeV for the nuclei with mass numbers 3, 4 and 5 respectively. If one nucleus of mass number 3 combines with one nucleus of mass number 5 to give two nuclei with mass number 4. Then
In a radioactive sample, what fraction of the initial number of radio active nuclei will be decayed after a time t = T 2 , where T=half life of radio active substance?
In a radio active material the activity at time t 1 is R 1 and at a later time t 2 , it is R 2 . If the decay constant of the material is λ , then
The mass of neutron and proton are 1.0087 amu and 1.0073 amu respectively and if two protons and two neutrons form a nucleus of helium whose mass is 4.0015 amu, Then find the binding energy of helium nucleus.
When an atom undergoes β + decay,
54 gm of a radioactive element decays to 18 gm in three hours. After six more hours, the amount of that element present will be
A proton and a neutron are both shot at 100 m/s towards a 6 12 C nucleus. Which particle, if either, is more likely to be absorbed by the nucleus?
A free nucleus of mass 24 amu emits a gamma photon (when initially at rest). The energy of the photon is 7 MeV. The recoil energy of the nucleus in keV is
Uranium ores contain one radium 226 atom for every 2 . 8 x 10 6 uranium 238 atoms. Calculate the half-life of U 92 238 given that the half-life of R 88 226 a is 1600 years ( R 88 226 a is a decay product of U 92 238 )
If 10% of a radioactive material decays in 5 days then the amount of the original material left after 20 days is approximately:
The minimum energy needed to break carbon of 12.000 amu into three is α particles (mass of α particle = 4.0038 amu)
Atomic mass number of an element is 232 and its atomic number is 90. The end product of this radioactive element is an isotope of lead P 82 208 b .The number of alpha and beta particles emitted is :
In fission, the percentage of mass converted into energy is about
1 kg of U 235 undergoes fission process. If energy released per event is 200 MeV, then total energy released is
If mass of U 235 = 235.12142 a m u , mass of U 236 = 236.1205 a m u and mass of neutron = 1.008665 amu, then the energy required to remove one neutron from the nucleus U 236 i s a b o u t
The half life of 131 I is 8 days, given a sample of 131 I at time t = 0, we can assert that
In the nuclear reaction 2 H e 4 + Z H e A Z + 2 Y A + 3 + Z ‘ M A ‘ M denotes
At any instant, the ratio of the amount of two radioactive substances is 2 : 1. If their half lives be respectively 12 h and 16 h, then after one days what will be the ratio of the substances?
The minimum frequency of a γ − r a y that causes a deuteron to disintegrate into a proton and a neutron is m d = 2.0141 a m u , m p = 1.0078 a m u , m n = 1.0087 a m u
Certain radio active substance reduces to 25% of its initial value in 16 days. Its half life is
If 7 8 th part of a radio active element decays in 168 sec, its half life is
The curve of binding energy per nucleon as a function of atomic mass number has a sharp peak for helium nucleus. This implies that helium
The graph between log R and log A where R is the nuclear Radius and A is the mass number is
If the speed of light were 2/3 of its present value. the energy released in a given atomic explosion will be decreased by a fraction
1 H 1 + 1 H 1 + 1 H 2 X + 1 e 0 + energy . The emitted particle is
The mass defect for the nucleus of helium is 0.0303 a.m.u. What is the binding energy per nucleon for helium in MeV?
The fission of a heavy nucleus gives, in general, two smaller nuclei, two or three neutrons, some β -particles and some γ -radiation. It is always true that the nuclei produced
In a fission reaction U 92 236 X 117 + Y 117 + n + n , the binding energy per nucleon of X and Y is 8.5 MeV where as of U 236 is 7.6 MeV. The total energy liberated will be about
The nuclear reaction H 1 1 + H 1 1 = He 2 4 (mass of deuteron = 2.0141 a.m.u. and mass of He = 4.0024 a.m.u.) is
The amount of energy approximately be released if all the atoms of 1kg of Deuterium could undergo fusion is (Assume in the fusion of Deuterium, 0.7% of mass is converted into energy)
Which of the following is in the increasing order for penetrating power?
During a negative beta decay
A radioactive nucleus undergoes a series of decays according to the scheme A α A 1 β A 2 α A 3 γ A 4 If the mass number and atomic number of A are 180 and 72 respectively, then what are these number for A 4 ?
If 92 U 238 undergoes successively 8 α -decays and 6 β -decays, then resulting nucleus is
When Th 228 90 transforms to Bi 212 83 , then the number of the emitted α and β – particles is, respectively
Which of the following processes represents a gamma-decay?
A nucleus decays by β + emission followed by a gamma emission. If the atomic and mass numbers of the parent nucleus are Z and A respectively, the corresponding numbers for the daughter nucleus are respectively.
In a radioactive reaction 92 X 232 82 Y 204 , the number of α -particles emitted is
Th 90 232 an isotope of thorium decays in ten stages emitting six α -particles and four β -particles in all. The end product of the decay is
A nucleus with Z= 92 emits the following in a sequence: α , β – , β – , α , α , α , α , α , β – , α , β + , β + , α . The Z of the resulting nucleus is
Three α -particles and one β -particle decaying takes place in series from an isotope Ra 236 88 . Finally the isotope obtained will be
A radioactive nucleus X 235 92 decays to Y 231 91 . Which of the following particles are emitted?
In the uranium radioactive series, the initial nucleus is U 238 92 and the final nucleus is U 206 82 . When the uranium nucleus decays to lead. the number of α -particles emitted will be
After 1 α and 2 β emissions
Which of the following is a correct statement?
The nucleus Cd 48 115 after two successive β – decays will give
In the given nuclear reaction A, B, C, D, E represents U 238 92 α Th A B β Pa C D E U 234 92
An element A decays into element C by a two-step process: A B + He 4 2 B C + 2 e – Then
The electron emitted in beta radiation originates from
In the given nuclear reaction, how many α and β particles are emitted X 235 92 Y 207 82 ?
The curve between the activity A of a radioactive sample and the number of active atoms N is
The graph between the instantaneous concentration (N) of a radioactive element and time (t) is
The half life period of radium is 1600 years. The fraction of a sample of radium that would remain after 6400 years is
What percentage of original radioactive atoms is left after five half-lives?
The radioactivity of a certain radioactive element drops to 1/64 of its initial value in 30 seconds. Its half-life is
The average life T and the decay constant λ of a radioactive nucleus are related as
If T is the half-life of a radioactive material, then the fraction that would remain after a time T 2 is
The half-life of Bi 210 is 5 days. What time is taken by 7 8 th part of the sample of decay?
The half life of a radioactive element which has only 1 32 of its original mass left after a lapse of 60 days is
A Sample contains 16 gm of a radioactive material, the half-life of which is two days. After 32 days, the amount of radioactive material left in the sample is
The half-life of polonium is 140 days. After how many days, 16 gm polonium will be reduced to 1 gm (or 15 gm will decay)?
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
An archaeologist analyses the wood in a prehistoric structure and finds that C 14 (Half-life = 5700 years) to C 12 is only one- fourth of that found in the cells buried plants. The age of the wood is about
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 Na 24 11 is 15 hrs. How much time does it take for 7 8 th of a sample of this isotope to decay?
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?
A radioactive substance has a half life of 60 minutes After 3hours, the fraction of atom that have decayed would be
After two hours, one- sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half-life of the isotope is
The half-life T 1 / 2 and the disintegration constant λ of a radioactive substance are related as
The half-life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be
Half lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and B have equal number of nuclei. After 80 minutes. the ratio of remaining number of A and B nuclei is
Half-life of a radioactive element is 10 days. The time during which quantity remains 1/10 of initial mass will be
In half-life of a radioactive element is 3 hours, after 9 hours its activity becomes
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
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?
The activity of a radioactive sample is measured as 9750 counts per minute at t = 0 and as 975 counts per minute at t = 5 minutes. The decay constant is approximately
The activity of a sample is 64 x 10 – 5 Ci . Its half—life is 3 days. The activity will become 5 x 10 – 6 Ci after
3.8 days is the half—life period of a Sample. After how many days, the sample will become l/8th of the original substance?
Plutonium decays with a half-life of 24000 years. If the plutonium is stored for 72000 years, then the fraction of plutonium that remains is
A radioactive substance has a half-life of 1 year. The fraction of this material, that would remain after 5 years will be
A radioactive sample has half-life of 5 years. Probability of decay in 10 years will be
If half-life of a substance is 3.8 days and its quantity is 10.38 gm. Then substance quantity remaining left after 19 days will be
Three fourth of the active decays in a radioactive sample in 3/4 sec. The half-life of the sample is
In a mean life of a radioactive sample
During mean life of a radioactive element, the fraction that disintegrates is
If a radioactive substance reduces to 1 16 of its original mass in 40 days, what is its halt-life?
1 mg gold undergoes decay with 2.7 days half- life period amount left after 8.1 days is
Certain radio-active substance reduces to 25% of its value in 16 days. Its half-life is
The half-life of a radioactive substance against α -decay is 1 . 2 x 10 7 s . What is the decay rate for 4 x 10 15 atoms of the substance?
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life?
A radioactive material has an initial amount 16 gm. After 120 days it reduces to 1 gm, then the half-life of radioactive material is
Half-life of a substance is 10 years. In what time, it becomes 1 4 th part of the initial amount?
If N 0 is the original mass of the substance of half-life period T 1 / 2 = 5 years , then the amount of substance left after 15 years is
The ratio activity of an element becomes 1/64 th of its original value in 60 sec. Then the half-life period is
The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its 1 16 th part?
A sample of radioactive element has a mass of 10 gm at an instant t = 0.The approximate mass of this element in the sample after two mean lives is
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
Activity of radioactive element decreased to one third of original activity R 0 in 9 years. After further 9 years. its activity will be
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?
The fraction f of radioactive material that has decayed in time t, varies with time t. The correct variation is given by the curve
A radioactive nucleus undergoes α -emission to form a stable element. What will be the recoil velocity of the daughter nucleus if V is the velocity of α -emission and A is the atomic mass of radioactive nucleus?
Half-life of a radioactive substance is 20 minutes. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximate
A and B are two radioactive substances whose half lives are 1 and 2 years respectively. Initially 10 gm of A and 1gm of B is taken. The time (approximate) after which they will have same quantity remaining is
Half life of a radio-active substance is 20 minutes. The time between 20% and 80% decay will be
After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activityof the sample in dps is
α-particle consists of :
An α – particle strikes an aluminium atom 13 27 A l . As a result, an unknown nucleus Z A X and a neutron are formed. Then values of A and Z are respectively
Two antiparticles x and y at rest combine and as a result two gamma photons are produced. If total energy of the gamma photons is 1.022 MeV, mass of each particle is
In the nuclear reaction Z A X + 0 1 n Z − 2 A − 3 Y + C , ‘C’ may be
Which of the following is not the property of a cathode ray?
Ratio of initial number of active nuclei of two radio active elements x and y is 8 :1. If half life of x is 1 hour and that of y is 2 hour, find the time after which the number of active nuclei of x and y will be the same.
The half life of a radio active substance is 10 days. This means that
A radioactive element has a half life of 2.5 hours. In 10 hours 1 gm of radioactive material is reduced to
Half life of a radioactive element is T. Then what fraction of initial number of active nuclei will decay in the time interval t = T to t = 2T?
Compare the radii of two nuclei with mass numbers 8 and 64. Also compare their densities.
Calculate the binding energy per nucleon of Cl 17 35 nucleus. Given that mass of Cl 17 35 nucleus = 34.98000 u, mass of proton = 1.007825 u, mass of neutron = 1.008665 u and 1 u is equivalent to 931 Mev.
A sample radio active subsistence has 10 6 radio active nuclei. It’s half-life is 20 sec. How many nuclei will remain after 10 seconds?
The Binding energy per nucleon of Li 3 7 and He 2 4 nuclei are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction Li 3 7 + H 1 1 He 2 4 + He 2 4 + Q the value of energy Q released is
An isolated radioactive source in the form a metal sphere of radius 1 mm undergoes β –ray decay at a constant rate of 6.25 × 10 10 /sec. Assuming 70% of the emitted β –particles escape from the source, time after which potential of the sphere rises by 1 V is
A radio active isotope X A Z decays in series by emitting 3 α -particles and two β – particles. The product will be
A sample of radioactive element has a mass of 10gm at an instant t=0. The appropriate mass of this element in the sample after two mean lives is
For a nuclear fusion reactor to run properly at a constant rate, it is best to pipe in Deuterium and Tritium separately at a rate
The rate of radioactive disintegration at an instant for a radioactive same of half life 2.2 × 10 9 s is 10 10 s –1 . The number of radioactive atoms in that sample at that instant is,
The binding energy per nucleon for Deuteron and Helium 1 H 2 and 2 He 4 are 1.1 MeV and 7 MeV respectively. The energy released when two Deuterons fuse to form a Helium nucleus is
The operation of a nuclear reactor is said to be critical if the multiplication factor (k) has a value of what?
Half life of a radio active element is 1200 yrs. It m 0 gm of radio active element existing now, m 0 /4 gm will remain radio active after
Which of the following is a stable nucleus?
Why is a fusion reaction difficult to perform?
In which of the following, weak nuclear forces appear?
What will happen in a time of 7 hours, if a radioactive substance containing a very large number of atoms has an average life of 7 hours?
Rest mass energy of a particle is 3 MeV and the particle is moving with a linear momentum of 2.133 × 10 − 21 K g − m / s . Then total energy of the particle is
Which of the following is positively charged?
The nuclear force between two nucleons
If M be the mass of the nucleus and m be the sum of individual masses of the nucleous forming the nucleus, then
In 10 hours 75% mass of a radio active sample is converted into a stable element. Then mean life of the radio active element is
If rest mass of helium nucleus is 4.0015 u, rest mass of proton is 1.0087 u, then binding energy of 2 4 He nucleus is
Half life of a radio active material is 5 hours. Then after what time number of undecayed nucleus of a sample of the radio active material will be equal to two times the number of decayed nucleus?
After one average life, what will be the ratio of number of undecayed nuclei to the number of decayed nuclei of a radioactive sample? [Take e = 2.7]
Count rate of a radioactive substance is 400 per minute. After some time the count rate is 123 per minute. If half life of the element is 2 hours, then number of nuclei decayed in this interval is
Packing fraction of a nucleus is 0.025 If its mass number is A 0 then mass of the nucleus is [u = Atomic mass unit]
A radio active nucleus emits both α and β + particles. Initial mass number of the nucleus is 260. After emission of α and β + particles, the final mass number of the nucleus is 236 and the nucleus becomes an isotone. Then number of emitted β + particles is
Nuclei of a radio active element are produced at the rate of α = 200 s − 1 . Initial number of active nuclei of the sample is 4000. It after one half life, rate of disintegration is equal to rate of production, then half life of the radio active element is
In the nuclear reaction Z A X Z − 1 A Y + β − + r ¯ + Energy, the emitted electron
Bi 210 has half-life of 5 days. The time taken for seven-eighths of a sample of Bi 210 to decay is :
80 kg of a radioactive material reduces to 10 kg in 1h. The decay constant of the material is
The electron emitted in β – radiation originates from
If average binding energy per nucleon of X and Y is 8.5 MeV whereas that of 92 236 U is 7.6 MeV. Then the total energy liberated in the following reaction is 92 236 U 117 X + 117 Y + n + n
When a β – -particle is emitted from a nucleus, the neutron-proton ratio:
A freshly prepared radioactive source of half life 2 hr emits radiation of intensity which is 64 times the permissible sale level. the minimum time after which it would be possible to work safely with this source is
The decay constant of radioactive sample is L The haif life and mean life of the sample are respectively given by
A sample contains 16 g of radioactive material, the half life of which is 2 days. After 32 days the amount of radioactive material left in the sample is
A star converts all of its He nuclei completely into oxygen nuclei. The energy released per oxygen nuclei is mass of He is 4.0026amu and mass of oxygen is 15.994 amu
