Let R1 be the radius of the second stationary orbit and R2 be the radius of the fourth stationary orbit of an electron in Bohr's model. The ratio $${{...

Given below are two statements Statement I : The law of radioactive decay states that the number of nuclei undergoing the decay per unit time is inver...

At any instant, two elements X1 and X2 have same number of radioactive atoms. If the decay constant of X1 and X2 are 10 $$\lambda$$ and $$\lambda$$ re...

The ratio of Coulomb's electrostatic force to the gravitational force between an electron and a proton separated by some distance is 2.4 $$\times$$ 10...

The graph which shows the variation of the de Broglie wavelength ($$\lambda$$) of a particle and its associated momentum (p) is

In the given nuclear reaction, the element X is $${}_{11}^{22}Na \to X + {e^ + } + v$$

Let T1 and T2 be the energy of an electron in the first and second excited states of hydrogen atoms, respectively. According to the Bohr's model of an...

A nucleus of mass number 189 splits into two nuclei having mass number 125 and 64. The ratio of radius of two daughter nuclei respectively is

A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding per nucleon of unfragmented nuclei is 7.6MeV while that ...

The half life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be :

When a uranium isotope $$_{92}^{235}U$$ is bombarded with a neutron, it generates $$_{36}^{89}Kr$$ three neutrons and :

For which one of the following, Bohr model is not valid?

The energy equivalent of 0.5 g of a substance is :

$$\alpha $$-particale consists of :

The total energy of an electron in an atom in an orbit is –3.4 eV. Its kinetic and potential energies are, respectively.

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 o...

The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is

Radioactive material 'A' has decay constant '8 $$\lambda $$' and material 'B' has decay constant '$$\lambda $$'. Initially they have same number of nu...

If an electron in a hydrogen atom jumps from the 3rd orbit to the 2nd orbit, it emits a photon of wavelength $$\lambda $$. When it jumps from the 4th ...

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 ...

When an $$\alpha $$-particle of mass m moving with velocity v bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucl...

Given the value of Rydberg constant is 107 m$$-$$1, the wave number of the last line of the Balmer series in hydrogen spectrum will be...

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then

In the spectrum of hydrogen, the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series is

If radius of the $${}_{13}^{27}$$ Al nucleus is taken to be RAl, then the radius of $${}_{53}^{125}$$Te nucleus is nearly

Consider 3rd orbit of He+ (Helium), using non-relativistic approach, the speed of electron in this orbit will be [given K = 9 $$ \times $$ 109 constan...

A radioactive X with a half life 1.4 $$ \times $$ 109 years decays to Y which is stable. A sample of the rock from a cave was found to contain X and Y...

Hydrogen atom in ground state is excited by a monochromatic radiation of $$\lambda $$ = 975 $$\mathop A\limits^ \circ $$. Number of spectral lines in...

The binding energy per nucleon of and nuclei are 5.60 MeV and 7.06 MeV respectively. In the nuclear reaction $${}_3^7Li + {}_1^1H \to {}_2^4He + _2^4H...

How does the Binding Energy per nucleon vary with the increase in the number of nucleons ?

An electron in hydrogen atom makes a transition n1 $$ \to $$ n2 where n1 and n2 are principal quantum numbers of the two states . Assuming Bohr's mode...

$$\alpha $$-particles, $$\beta $$-particles and $$\gamma $$-rays are all having same energy. Their penetrating power in a given medium in increasing ...

Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is

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 b...

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 ...

The transition from the state n = 3 to n = 1 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the tran...

The half life of a radioactive nucleus is 50 days. The time invertal (t2 $$-$$ t1) between the time t2 when $${2 \over 3}$$ of it has decayed and the ...

A mixture consists of two radioactive materials A1 and A2 with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A1 and 160...

If the nuclear radius of 27Al is 3.6 fermi, the approximate nuclear radius of 64Cu in fermi is

Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The r...

An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of p...

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?

Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0. number of P species are 4 N0 and that of Q are N0. Hal...

An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material havin...

The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The a...

The half life of a 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...

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

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

A nucleus $${}_n^mX$$ emits one $$\alpha $$ particle and two $$\beta $$ particles. The resulting nucleus is

Fusion reaction takes place at high temperature because

The decay constant of a radio isotope is $$\lambda $$. If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which hav...

The binding energy per nucleon in deuterium and helium nuclei are 1.1 MeV and 7.0 MeV, respectively. When two deuterium nuclei fuse to form a helium n...

The energy of a hydrogen atom in the ground state is $$-$$ 13.6 eV. The energy of a He+ ion in the first excited state will be

The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) a...

The mass of a $${}_3^7Li$$ Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of $${}_3^7Li$$ n...

The energy of a hydrogen atom in the ground state is $$-$$ 13.6 eV. The energy of a He+ ion in the first excited state will be

An alpha nucleus of energy $${1 \over 2}$$ mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucl...

In the nuclear decay given below $${}_Z^AX \to {}_{Z + 1}^AY \to {}_{Z - 1}^{A - 4}B{}^ * \to {}_{Z - 1}^{A - 4}B,$$ the particles emitted in the seq...

In a Rutherford scattering experiment when a projectile of charge z1 and mass M1 approaches a target nucleus of charge z2 and mass M2, the distance of...

The ionization energy of the electron in the hydrogen atom in its ground state is 13.6 eV. The atoms are excited to higher energy levels to emit radia...

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an

If M(A; Z), Mp and Mn denote the masses of the nucleus $${}_Z^AX,$$ proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represen...

Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be

The ground state energy of hydrogen atom is $$-$$ 13.6 eV. When its electron is in the first excited state, its excitation energy is

Two radioactive materials X1 and X2 have decay constants $$5\lambda $$ and $$\lambda $$ respectively. If initially they have the same number of nuclei...

Two radioactive substances A and B have decay constants 5$$\lambda $$ and $$\lambda $$ respectively. At t = 0 they have the same number of nuclei. The...

In a radioactive decay process, the negatively charged emitted $$\beta $$-particles are

In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential $$V$$ and then made to descr...

A nucleus $${}_Z^AX$$ has mass represented by M(A, Z). If Mp and Mn denote the mass of proton and neutron respectively and B.E. the binding energy in ...

If the nucleus $${}_{13}^{27}Al$$ has a nuclear radius of about 3.6 fm, them $${}_{32}^{125}Te$$ would have its radius approximately as

The total energy of electron in the ground state of hydrogen atom is $$-$$ 13.6 eV. The kinetic energy of an electron in the first excited state is

Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. ...

In a radioactive material the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is $$\lambda $$, then ...

The binding energy of deuteron is 2.2 MeV and that of $${}_2^4$$He is 28 MeV. If two deuterons are fused to form one $${}_2^4$$He then the energy rele...

The radius of germanium (Ge) nuclide is measured to be twice the radius of $${}_4^9$$Be. The number of nucleons in Ge are

In the reaction $${}_1^2$$H + $${}_1^3$$H $$ \to $$ $${}_2^4$$He + $${}_0^1$$n, if the binding energies of $${}_1^2$$ H, $${}_1^3$$H and $${}_2^4$$He ...

The total energy of an electron in the first excited state of hydrogen atom is about $$-$$ 3.4 eV. Its kinetic energy in this state is

Which one of the following pairs of nuclei are isotones ?

In any fission process the ratio mass of fission products mass of parent nucleus is ...

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

Energy levels A, B and C of a certain atom corresponding to increasing values of energy i.e. EA < EB < EC. If $$\lambda $$1, $$\lambda $$2 and...

If M(A; Z), Mp and Mn denote the masses of the nucleus $${}_Z^AX,$$ proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represen...

A nucleus represented by the symbol $${}_Z^AX$$ has

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 ...

The Bohr model of atoms

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

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The Coulomb force $$\overrightarrow F $$ between the two i...

Solar energy is mainly caused due to

The volume occupied by an atom is greater than the volume of the nucleus by a factor of about

A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element in the sample after two mean lives is

The mass of proton is 1.0073 u and that of neutron is 1.0087 u (u = atomic mass unit). The binding energy of $${}_2^4$$ He is (Given helium nucleus m...

The mass number of a nucleus is

In which of the following systems will the radius of the first orbit (n = 1) be minimum ?

A nuclear reaction given by ZXA $$ \to $$ z+1YA + $$-$$1e0 + $$\overline v $$ represents...

Which of the following are suitable for the fusion process ?

A sample of radioactive element containing 4 $$ \times $$ 1016 active nuclei. Half life of element is 10 days, then number of decayed nuclei after 30 ...

A deutron is bombarded on 8O16 nucleus then $$\alpha $$-particle is emitted. The product nucleus is

Which rays contain (positive) charged particles ?

X(n, $$\alpha $$) $${}_3^7$$Li, then X will be

Half life of a radioactive element is 12.5 hour and its quantity is 256 g. After how much time its quantity will remain 1 g?

The interplanar distance in a crystal is 2.8 $$ \times $$ 10$$-$$8 m. The value of maximum wavelength which can be diffracted

Mn and Mp represent the mass of neutron and proton respectively. An element having mass M has N neutrons and Z protons, then the correct relation will...

The energy of hydrogen atom in nth orbit is En then the energy in nth orbit of singly ionised helium atom will be

Energy released in nuclear fission is due to

For the given reaction, the particle X is $$_6{C^{11}} \to {}_5{B^{11}} + {\beta ^ + } + X$$

Nuclear fission is best explained by

When an electron does transition from n = 4 to n = 2, then emitted line spectrum will be

The relation between $$\lambda $$ and T1/2 as (T1/2 $$ \to $$ half life)

The life span of atomic hydrogen is

Maximum frequency of emission is obtained for the transition