The quantity which is not conserved in a nuclear reaction is

The ratio ofAngular momentum of an electron is the 2nd state and 3rd excited state of H-atom

Which of the following spectral series of H-atom has the range in visible region

If one move up in the energy states of a Hlike atom, the energy difference between two consecutive energy states

During k-electron capture reaction x-rays are emitted due to

Moderator used in a nuclear reactor is

Nuclear force is

The number of quantum energy states in a Na atom

‘Rhc’has the dimension of (R-Rydberg’s const, h-Planck’s const, c-velocity of light)

The concept of circular orbit of electrons around the nucleus was initially given by

According to Bohr’s theory, the variation of perimeter(s) of the electronic orbit with the order of orbit (n) in a particular atom is

Nuclear volume of a nucleus having mass number 8 is V. Nuclear volume of the nucleus having mass number 64 will be

Two samples having their initial activities in the ratio 1 : 4 have half life periods 15 years and 10 years respectively. The time after which both posses equal activity is

The half life of a radioactive nucleus is 3 hours. In 9 hours, its activity will be reduced to a factor of

Two substance having number of nuclei in the ratio 2 : 3 have equal activity at some instant.The half life period of both the substances may be respectively

An electron in 20th state of a H-like atom tries to come to its 5th state. The number of possible transitions are

If principal quartum number n > 5 are not allowed in nature, the number of possible elements are

Binding energy per nucleon is 8.5 MeV for A = 240 and 7.6 MeV for A = 120. A nucleus having A = 240 breaks into two nuclei having nearly equal masses. The amount of energy released in the process is

If the shortest wavelength of Lyman series of H atom is x, then the wavelength of first member of Balmer series of H atom will be

When electron and positron travelling in opposite directions with equal speed annihilate (destroy) each other, they cannot produce just one gamma photon, because it will violate

A container is filled with a radioactive substance for which the half-life is 2 days. A week later, when the container is opened, it contains 5 grams of the substance. Approximately how may grams of the substancewere initially placed in the container?