A radioactive source in the form of a metallic sphere of radius 2 cm emits β – particles at the rate of 2 × 10 10 particles per second. The source is electrically insulated. How long will it take for its potential to be raised by 5 V. Assuming that 50% of emitted β -particle escapes the source.
A star initially has 3 × 10 20 deuterons. It produces energy via the process 1 H 2 + 1 H 2 1 H 3 + p and 1 H 2 + 1 H 3 2 H e 4 + n . Find the total energy released during the deuteron supply of star is exhausted (mass of 2 H e 4 = 4.001 a m u , 1 H 1 = 1.007 a m u , 1 H 2 = 2.014 a m u , 0 n 1 = 1.008 a m u )
Determine the amount of 84 P o 210 necessary to provide a source of α particles of 10 milli-curie strength if mean life of 84 P o 210 is 1.72 × 10 7 s e c
The radioactivity of a given sample of whisky due to tritium T 1 / 2 = 12.5 y e a r s was found to be only about 4% of that measured in a recently purchased bottle marked 7 years old. The sample must have been prepared about given log5=0.698
When a slow moving neutron collides with Uranium 235 atom 235 92 U , following reaction occurs. 0 1 n + 92 235 U ⟶ 92 236 U ∗ ⟶ 40 99 Zr + 52 134 Te + 3 0 1 n If kinetic energy of neutrons is neglected (as it is very small), then the Q of reaction is 37 x K MeV. The value of K is . Use following data. m U 235 = 235 . 0439 u , m n = 1 . 0087 u , m Z r 99 = 98 . 9165 u , m T e 134 = 133 . 9115 u .
After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is
In the chemical analysis of a rock the mass ratio of two radioactive isotopes is found to be 100:1. The mean lives of the two isotopes are 4 × 10 9 yr and 2 × 10 9 yr, respectively. If it is assumed that at the time of formation the atoms of both the isotopes were in equal proportion, the age of the rock p × 10 10 yr, where the value of p is … Take, ratio of the atomic weights of the two isotopes is 1.02:1.)
The disintegration rate of a certain radioactive sample at any instant is 4750 disintegrations per minute. 5 min later, the rate becomes 2700 min -1 . Then, the half-life of the sample (in min) is…….. ln 475 200 = 0 . 56
A sample of 2 gm of Ac (227) with a half life of 21.8 years decay to Fe (223) by emitting α particles. After what time does the activity reduces to 12.5% of the original activity?
A nucleus with Z=92 emits the following in a sequence α , β − , β − , α , α , α , β − , β − , α , β + , β + and α . The atomic number of the final element will be
In the binding energy curve P,Q,R,S,T,U correspond to different nuclei. Which of the following reactions are exothermic P + Q R R P + Q S + T U U S + T
The age of an ancient tree is determined by measuring the
The counting rate observed from a radioactive source at t=0 was 1600 counts per second and at t=8s it was 100 counts per second. The counting rate observed as counts per second at t=4sec will be
A radioactive nuclei A produces a daughter “B”. Which decays to a stable product “C” then the variation of a population of A,B & C with time is
A consecutive reaction A k 1 B k 2 C is characterized by
The half life of a radio active nuclide is 30 hr’s. What fraction of original activity will remain after 60 hr’s ?
The half-life of a radioactive material is four hours. If the initial amount is 400g then after 24 hours it will remain
A radioactive element reduces to 12.5% of its initial mass in 900 yr’s. Find the half-life period in years
If the half-life of a radioactive substance is 238.5 min. Then the mean-life in min
A certain substance decay to 1 16 of its initial activity in 24 days . Calculate its mean life ( approximately in days)
Starting with a sample of pure C u 66 , 7 / 8 part of sample decay’s into Zn in 21 minutes. The corresponding mean-life is
If one starts with one curie of radioactive substance of half – life 12 hr’s , the activity left after a period of 1 week will be
One gram of Radium emits 3 . 7 × 10 10 α – particles per second. Calculate mean life of radium. Given Atomic mass of radium = 226
In a reactor, 2kg of 92 U 235 fuel is fully used up in 30 days. The energy released per fission is 200 MeV. Given that the Avogadro number, N = 6.023 × 10 26 per kilo mole and 1 e V = 1.6 × 10 − 19 J . The power output of the reactor is close to
Given: mass number of gold – 197, density of gold – 19.7 g cm -3 , Avogadro’s number – 6 x 10 23 . The radius of the gold atom is approximately:
When U 235 undergoes fission, 0.05% of its original mass is changed into energy. How much energy is released if 2kg of U 235 undergoes fission?
If atomic mass of Th is 232 and its atomic number is 90. If it forces 4 β -particles and some α -particles. The mass number of final stable element is 208 and atomic number 82. How many α -particles are emitted during this process?
A radio isotope will not emit
In which of the following decays n/p ratio increases
In which of the following decays n/p ratio decreases
The nuclei of which one of the following pairs of nuclei are isotones
By emitting a positron the n/p ratio
92 U 238 decays successively to form 90 T h 234 , 91 P a 234 , 92 U 234 . The sequence of radiations emitted is
In a star about 5 billion kg of matter is converted into energy each second. The power output of the star in watt is
If the half lives of a radioactive elements for α and β are 3 years and 6 years respectively, then percentage of the elements that remains after 10 years will be
The graph of ln R R 0 verses ln A w h e r e R − r a d i u s , A − m a s s n u m b e r is
Consider the nuclear reaction 3 L i 7 + 1 H 1 2 2 H e 4 . The relevant atomic masses are 7 L i = 7.018 a m u , 1 H = 1.0080 , 4 H e = 4.004 a m u . 0.5 g m s of 1 H 1 completely consumed in the reaction along with sufficient amount of 7 L i . Find energy released.
From the graph ln d N d t versus t, the mean life of the radioactive sample ( in sec )is
A nuclear reactor containing U235 produces 20 MW power. Calculate the fission rate assuming that 200 MeV of useful energy is released in one fission?
How much energy must have a bombarding proton to cause the reaction 3 L i 7 + 1 H 1 4 B e 7 + 0 n 1 − 1.65 M e V
Consider a hypothetical case of a radio nuclide “A” which produce a daughter “B” which decay’s to a stable product C. The half life of B is 4 times that of “A”. Take initial population of both ‘B’ and ‘C’ to be zero. The ratio of population of “B” to that of “A” at the instant the population of B becomes maximum is
An α – particle collides with a stationary lithium, as 4 H e + 7 L i 10 B + n . If Q value of this reaction is Q = − 2.5 M e V . Find the minimum value of kinetic energy of α – particle required for the reaction?
In a nuclear reactor fast moving neutron ( m n ) moving at a speed V , hits a moderator nucleus (M) which is originally static and gets scattered elastically by 180 0 . Find the kinetic energy of the neutron after collision?
A radioactive sample has half-life of 3yr’s. Probability of decay in 9yr’s.will be
The activity of a radioactive sample is 1.6 curie and its half-life is 5 days. Its activity after 20 days will be
A certain element has a half-life of 28 days. Find its average life in days
A radioactive element has half-life period 700 yr’s. After 4200 yr’s what amount will remain?
The percentage of quantity of a radioactive material that remains after 4 half lives will be
A Geiger counter placed above a radioactive sample register’s 678 counts per minute. How many counts per minute will it register after five half lives have passed
At given instant there are 50% undecayed radioactive nuclei in a sample. After 20sec, the number of undecayed nuclei reduces to 12.5% . Calculate mean life of the nuclei.
The half life of radium 1640 years and its atomic weight is 227 kg per kilo mol. The number of atom’s that will decay from its 1 gm sample per minute will be
A sample of radioactive element contains 5 × 10 10 active nuclei. If half life of element is 10 days, then the number of decayed nuclei after 40 days is
The half life of a sample of a radioactive substance is 2 hour. If 8 × 10 10 atoms are present at t = 0 , then the number of atoms decayed in the duration t = 2 hours to t = 6 hours will be
The count rate of a Geiger Muller counter for the radiation of a radioactive material of half life 30 minutes decreases to 5 s – 1 after 2 hour’s . The initial count rate was
Two radioactive substance A and B have decay constants 9 λ and 3 λ respectively. At t = 0 , they have the same number of nuclei. The ratio of number of nuclei of A to these of B will be 1 e 2 after a time interval of
If a radioactive sample initially contains 8 . 00 × 10 14 parent nuclei with a half life of 7.00 hr’s , how many parent nuclei remain in 24.0 hr’s later ?
The half life of Au 198 is 2.9 days. Calculate the average life
Number of nuclei of radioactive substance are 900 and 810 at times t=0 and t=3 sec. Then number of nuclei at time t = 6 sec will be
The half life of a certain radioactive isotope is 28 hr’s . What fraction of sample would remain after 7 h ?
The activity of a radioactive sample falls from 700 s – 1 to 500 s – 1 in 30 minute. Its half-life is close to:
In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining after t/2 is :
The radius R of a nucleus of mass number A can be estimated by the formula R = ( 1 . 3 × 10 – 15 ) A 1 / 3 m . It follows that the mass density of a nucleus is of the order of : M prot ≅ M neut = 1 . 67 × 10 – 27 kg
Find the Binding energy per neucleon for 50 120 S n . Mass of proton m p = 1.00783 U , mass of neutron m n = 1.00867 U and mass of tin nucleus m S n = 119.902199 U . (take 1U = 931 MeV)
Activities of three radioactive substances A,B and C are represented by the curves A,B and C in the figure . Then their half lives T 1 2 A :T 1 2 B :T 1 2 C : are in the ratio :
A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the second is 100 s. The effective half life of the nucleus is close to :
A radioactive nucleus A with a half life T decays into a nucleus B. At t=0 , there is no nucleus of B. At some time t , the ratio of the number of nuclei of B to that of A is 0.3 then, t is given by
The Q-value of the fusion reaction, He 4 + He 4 Be 8 is – 9 . 315 × 10 x e V . Find the value of x . Atomic mass of Be 8 is 8 . 0053 u and that of He 4 is 4 . 0026 u
The half life period of a radioactive element X is the same as the mean life time of another radioactive element Y. Initially both of them have the same number of atoms. Then,
A parent radioactive nucleus A (decay constant D A ) converts into a radioactive nucleus B of decay constant D B . Initially number of atoms of B is zero. At any time N A , N B are number of atoms of nuclei A and B respectively. Then maximum value of N B is
M x a n d M y denote the atomic masses of the parent and daughter nuclei respectively in a radio active decay. The Q value of a β − decay is Q 1 and for β + decay is Q 2 . If m e denotes the mass of electron, then which of following statements is correct?
Nuclei of radioactive element A are produced at rate ‘ t 2 ’ at any time t. The element A has decay constant λ . Let N be the number of nuclei of element A at any time t. At time t = t o , d N d t is minimum. Then the number of nuclei of element A at time t=t 0 is:
In the fusion reaction 1 2 H + 1 2 H ⟶ 2 3 He + 0 1 n , the masses of deuteron, helium and neutron expressed in amu are 2.015, 3.017 and 1.009, respectively. If 1g of deuterium undergoes complete fusion, then the amount of total energy released is 9 x 10 n kJ. Find the value of n.
