Radioactivity

A nucleus nXᵐ emits one α- particle and two β- particles. The resulting nucleus is

1 curie is equal to

In atom bomb, the reaction which occurs is

During negative β-decay

By the successive disintegration of ₉₂U²³⁸, the final product obtained is ₈₂Pb²⁰⁶, then how many number of α and β-particles are emitted?

A radioactive nucleus emits a beta particle. The parent and daughter nuclei are

In which of the follows decays, the element does not change?

What is the energy released by fission of 1 g of U²³⁵? (Assume 200 MeV energy is liberated on fission of 1 nucleus)

The kinetic energy of α-particle emitted in the α-dacay of ₈₈Ra²²⁶ is [given, mass number of Ra=222 u]

In a nuclear reactor, the number of U²³⁵ nuclei undergoing fission per second is 4 x 10²⁰. If the energy released per fission is 250 MeV, then the total energy released in 10 h is (1 eV = 1.6 x 10⁻¹⁹ J)

Nuclear fission is not found in

The energy released by the fission of one uranium atom is 200 MeV. The number of fission per second required to produce 6.4 W power is

The half life of radium is 1620 yr and its atomic weight is 226 kg per kilo mol. The number of atoms that will decay from its 1g sample per second will be (take, Avogadro’s number, Nᴀ = 6.023 x 10²³ atom/kilo mol)

The relationship between decay constant λ and half-life T of a radioactive substance is

For the radioactive nuclei that undergo either α or β decay, which one of the following cannot occur?

In a given reaction,
ᴢXᴬ → ᴢ₊₁Yᴬ → ᴢ₋₁Kᴬ⁻⁴ → ᴢ₋₁Kᴬ⁻⁴
The radioactive radiations are emitted in the sequence of

The nuclear fusion reaction between deuterium and tritium takes place

The S.I. unit of radioactivity is

When ₉₀Th²²⁸ transforms to ₈₃Bi²¹², the number of emitted α and β particles are respectively

A U²³⁵ reactor generates power at a rate of P producing 2 x 10¹⁸ fission per second. The energy released per fission is 185 MeV. The value of P is

In radioactive element, β-rays are emitted from

The purpose of using heavy water in nuclear reactor is

The phenomenon of radioactivity

Pick out the correct statements from the following
I. Electron emission during β-decay is always accompanied by neutrons
II. Nuclear force is charge independent
III. Fusion is the chief source of stellar energy

A nucleus ᴢXᴬ emits an α- particle with velocity v. The recoil speed of the daughter nucleus is

A radioactive substance emits 100 beta particles in the first 2s and 50 beta particles in the next 2s. The mean life of the sample is

If the half-life of a material is 10 yr, then in what time, it becomes 1/4th part of the initial amount

If t₁/₂ is the half-life of a substance, then t₃/₄ is the time in which

Which of the following atoms has the lowest ionisation potential?

A nucleus of mass number 220, initially at rest, emits an α-particle. If the Q-value of the reaction is 5.5 MeV, then the energy of the emitted α-particle will be

which of the following can not be emitted by radioactive substances during their decay?

In the reaction ₉₂U²³⁴ → ₈₇Y²²², how many α-particle and β-particles are emitted respectively?

The half life of radium is about 1600 year. Of 100 gram of radium existing now, 25g will remain unchanged after

In a radioactive decay process, the negatively charged emitted β- particles are

Two radioactive materials X₁ and X₂ have decay constants 5λ and λ respectively. If initially they have the same number of nuclei, then the ratio of number of nuclei of X₁ to that of X₂ will be (1/e) after a time

A radioactive substance has a half-life of four months. Three-fourth of substance will decay in

The half life of radioactive isotope ‘X’ is 50 years. It decays to another element ‘Y’ which is stable. The two elements ‘X’ and ‘Y’ were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be

Curie is the unit of

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

A mixture consists of two radioactive materials A₁ and A₂ with half lives of 20s and 10s respectively. Initially the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after:

₉₂U²³⁴ has 92 protons and 238 nucleons. It decays by emitting an alpha particle and becomes

The fossil bone has a ¹⁴C:¹²C ratio, which is [1/16] of that in a living animal bone. If the half-life time of ¹⁴C is 5730 years, then the age of the fossil bone is

The ‘rad’ is the correct unit used to report the measurement of

Solar radiation is

In gamma ray emission from a nucleus

The half-life period of a radio-active element X is same as the mean life time of another radio-active element Y. Initially they have the same number of atoms. Then

A radioactive sample S₁ having an activity of 5 μCi has twice the number of nuclei as another sample S₂ which has an activity of 10 μCi. The half lives of S₁ and S₂ can be

₉₂U²³⁵ undergoes successive disintegrations with the end product of ₈₂P²⁰³. The number of α and β-particles emitted are

Which one of the following statements is true, if half-life of a radioactive substance is 1 month?

The radioactivity of a certain material drops to 1/16 of the initial value in 2 hours. The half-life of this radio nuclide is

A radioactive nucleus of mass M emits a photon of frequency v and the nucleus recoils. The recoil energy will be

In nuclear fusion, two nuclei come together to form a large nucleus. Which of the following is a correct equation for such a reaction?

The moderator in a reactor

α- particles, β – particles and γ – rays are all having same energy. Their penetrating power in a given medium in increasing order will be

A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 a.m.u. The energy liberated per a.m.u. is (Given : 1 a.m.u. = 931 MeV)

An alpha nucleus of energy 1/2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to

Moderator used in nuclear reactor is

When an α-particle of mass m moving with velocity ν bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on m as

The control rods used in a nuclear reactor can be made up of

The cadmium rods are used in nuclear reactor to

Which of the following is suitable for the fusion process?

An atom bomb weighing 1 kg explodes releasing 9 x 10¹³ J of energy. What percentage of mass is converted into energy?

In nuclear fission, the percentage of mass converted into energy is about

What is the Q-value of the reaction?
¹H+⁷Li → ⁴He+⁴He
The atomic masses of ¹H,⁴He and ⁷Li are 1.0078254u, 4.0026034u and 7.016004u, respectively.

If in a nuclear fusion process, the masses of the fusing nuclei be m₁ and m₂ and the mass of the resultant nucleus be m₃, then

Fission of nuclei is possible because the binding energy per nucleon in them

The decay constant of a radio isotope is λ. If A₁ and A₂ are its activities at time t₁ and t₂ respectively, the number of nuclei which have decayed during the time (t₁ – t₂):

The power obtained in a reactor using U²³⁵ disintegration is 1000 kW. The mass decay of U²³⁵ per hour is

Fusion reaction takes place at high temperature because

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 of 1 : 7 in a sample of a the given rock. The age of the rock is estimated to be

On bombarding U²³⁵ by slow neutron, 200 MeV energy is released. If the power output of atomic reactor is 1.6 MW, then the rate of fission will be