LMS

To ionize hydrogen atom from its ground state energy required is

The ratio of the longest and shortest wavelengths of the Lyman series is approximately

For X– rays which of the following is not correct:

In Bohr’s model, the atomic radius of the first orbit is ; then the radius of the third orbit is:

Characteristic X-rays are produced due to

Number of the emission spectra are

What will be the energy of accelerated electron used to produce x-rays if accelerating potential is 2KV?

The atom is excited to an energy level E1 from its ground state energy level Eo, the wavelength of the radiations emitted is

Due to emission of

The source of energy in sun is

Which of the following isotopes is normally fissionable?

The more readily fissionable isotope of uranium has an atomic mass of

The amount of energy that must be supplied to a nucleus if the nucleus is to be broken into protons and neutrons is called

A quark cannot have charge

Emission of alpha decay from a radioactive substance cause:

The activity of radioactive sample:

In nuclear fission reaction, when the products are and the number of neutrons emitted is

– radiation are emitted due to

During nuclear changes which of the following laws remain applicable

What percentage of radioactive substance is left after three half-lives?

If 20 g of a radioactive substance reduces to 10 g in 4 minutes, then in what time will 80 g of the same substance reduce to 10 g?

The rate of decay of radioactive element at a given instant of time is 103 disintegration/second. If the half-life of this element is 1 second, then the rate of decay after 2 second will be

Among the three types of radioactive radiation, which have strongest penetration power?

A zirconium nucleus emits -particle. The product nucleus is also emits -particle. What is the final resulting nucleus of these two decays?

Protons are accelerated from rest by a potential difference 4 KV and strike a metal target. If a proton produces one photon on impact of minimum wavelength λ1 and similarly an electron accelerated to 4 kV strikes the target and produces a minimum wavelength λ2 then

What are the correct descriptions of a -ray and a -particle?

The initial activity of a sample of a radioactive isotope containing N0 nuclei is A0. What is the number of unchanged nuclei when the activity has declined to ?

Which one of the series of hydrogen spectrum is in the visible region?

The energy levels of the hydrogen spectrum is shown in figure. There are some transitions A, B, C, D and E. Transition A, B and C respectively represent

Which of the following is true for number of spectral lines in going from Lyman series to P fund series?

The amount of energy released in the fusion of four hydrogen nuclei to form an alpha particle is equal to

Hydrogen atom does not emit X-rays because

X-rays were discovered by

One eight of the initial mass of certain radioactive isotope remains un-decayed after one hour. The half-life of the isotope in minutes is

The penetrating power of X-rays increases with the

X-rays cannot be deflected by means of an ordinary grating due to

Curie is a unit of

Three quarks make up a

If the filament current in X-ray tube is increased, then cut off wavelength

Paschen series is obtained when all the transitions of electron terminate on.

The value of Rydberg’s constant is:

Sum of the charge of two up and one down quark is equal to

If No radioactive atoms are present in a sample initially. After five half-lives radioactive atoms left to decay are

Activity of a sample is initially 320 counts per second. At the end of 90 minutes it gives 40 counts per second. What is the half-life of the element in sample?

Which of given is not correct

The emission of β-particle from polonium-218 results in the formation of

The fusion process is possible at high temperatures because at high temperatures

In which of the following transitions will the wavelength be minimum?

The activity from a radioactive source is found to full by 0.875 of its initial activity in 210 s. What is the half-life of the source?