Taking the Bohr radius as a₀ = 53pm, the radius of Li⁺⁺ ion its ground state, on the basis of Boh''s model, will be about

For the ground state, the electron in the H-atom has an angular momentum =h, according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,

Consider aiming a beam of free electrons towards free protons. When they scatter, an electron and a proton cannot combine to produce a H-atom,

The series of hydrogen spectrum which lies in visible region is

Consider a hydrogen atom with its electron in the nth orbit. An electromagnetic radiation of wavelength 90 nm is used ionize the atom. If the kinetic energy of the ejected electron is 10.4 eV, then the value of n is (h_c = 1242 eV nm)

If a star can convert all the He nuclei completely into oxygen nuclei, the energy released per oxygen nucleus is [Mass of He nucleus is 4.0026 amu and mass of Oxygen nucleus is 15.9994 amu]

A radioisotope X with a half life \(1.4\times { 10 }^{ 9 }\) 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

How is impact parameter related to the scattering angle?

Name the series of hydrogen spectrum, which has least wavelength.

Name the series of hydrogen spectrum which lies in the visible region of electromagnetic spectrum?

How many coulombs of charge is carried by 1kg of electrons?

The mean life of a radioactive sample is \({ T }_{ m }\). What is the time in which 50% of the sample would get decayed?

What is the impact parameter for scattering of \(\alpha \)- particle by \(180°\)?

Calculate the energy equivalent of 1 a.m.u. in MeV.

Give the order of magnitude of nuclear mass density and average atomic mass density. Compare these densities with the typical mass density of solids, liquids, and gases (at ordinary temperature and pressure).

Why is \(_{ 92 }{ { U }^{ 238 } }\) not suitable for chain reaction?

Nuclear fusion is not possible in laboratory.Why?

'The half life \(_{ 6 }^{ 14 }{ C }\) is 5700 years.' What does it mean ?
Two radioactive nuclei X and Y initially contain an equal number of atoms. Their half life is 1 hour and 2 hours respectively. Calculate the ratio of their rates of disintegration after two hours.

For the \({ \beta }^{ + }\)  (positron) emission from a nucleus, there is another competing process known as electron capture (electron from an inner orbit say the K-shell)is captured by the nucleus and a neutrino is emitted:
\({ e }^{ + }{ _{ Z }{ { X }^{ A } } }\rightarrow _{ Z-1 }{ Y^{ A } }+\nu \)
Show that if \({ \beta }^{ + }\)  emission is energetically allowed, electron capture is necessarily allowed but not vice versa,

An alpha particle of energy 4MeV is scattered through \(180°\) by a gold foil (Z = 79). Calculate the maximum volume in which positive charge of the atom is likely to be concentrated?

Calculate the wavelength of photon emitted when an electron jumps from 3^rd orbit to 2nd orbit. Take \(R=1.097\times { 10 }^{ 7 }{ m }^{ -1 }\). Is this photon visible?

A nuclear reactor is a powerful device, wherein nuclear energy is utilised for peaceful purposes. It is based upon controlled nuclear chain reaction. The nuclear chain reaction is controlled by the use of control rods (of boron or cadmium) and moderators like heavy water, graphite, etc. The whole reactor is protected with concrete walls 2 to 2.5 metre thick, so that radiations emitted during nuclear reactions may not produce harmful effects.
Read the above passage and answer the following questions:
(i) Give any two merits of nuclear reactors.
(ii) What is radiactive waste?
(iii) Why do people often oppose the location site of a nuclear reactor? What do you suggest?

On the basis of Bohr's theory of H-atom, total energy of electron in a stationary orbit is given by the relation
Where, n is the number of orbits. It is clear that total energy of electron in a stationary orbit is negative which implies that electron is bound to the nucleus and is not free to leave it. The value of negative energy decreases as n increases.
Read the above p[assagr and answer the following questions:
(i) What is the total energy of electron in ground state of hydrogen atom? What does it indicate?
(ii) Why does energy required to remove an electron is smaller when atom is in any one excited state?