A free neutron decays into a proton, an electron and
A beta particle
An alpha particle
An anti-neutrino
A neutrino
The most penetrating radiation of the following is
Gamma-rays
Alpha particles
Beta-rays
X-rays
Which of the following is used as a moderator in nuclear reactos ?
Cadmium
Heavy water
Uranium
Plutonium
Half-lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and have equal number of nuclei. After 80 minutes the ratio of remaining numbers of A and B nuclei is
1 : 16
4 : 1
1 : 4
1 : 1
Atomic weight of Boron is 0.81 and it has two isotopes . Then the ratio of in nature would be
19 : 8 1
10 : 11
15 : 16
81 : 19
Light of wavelength 5000 Å falls on a sensitive plate with photo-electric work function of 1.9 eV. The kinetic energy of the photo-electron emitted will be
0.58 eV
2.48 eV
1.24 eV
1.16 eV
Alpha-particle are
Protons
Positron
Neutrally charged
Ionized helium atoms
As the intensity of incident light increases
Photoelectric current increase
K.E. of emitted photoelectrons increases
Photoelectric current decreases
K.E. of emitted photoelectrons decreases
The photoelectric work function for a metal surface is 4.125 eV. The cut off wavelength for this surface is
4125 Å
3000 Å
6000 Å
2062.5 Å
Who indirectly determined the mass of the electron by measuring the change of the 3electron ?
Millikan
Rutherford
Einstein
Thomson
When an electron jumps from the fourth orbit to the second orbit, one gets the
Second line of Lyman series
Second line of paschen series
Second line of Balmer series
First line of P fund series
Atomic hydrogen has life period of
One minute
One day
A fraction of a second
One hour
It is possible to understand nuclear fission on the basic of the
Liquid drop model of the nucleus
Meson theory of the nuclear forces
Proton-proton cycle
Independent particle model of the nucleus
The energy of hydrogen atom in nth orbit is , then the energy in nth orbit of single ionized helium atom will be
Which of the following moving particles (moving with same velocity) has largest wavelength of matter waves?
Electron
-particle
Proton
Neutron
Which one of the following statements is not true for cathode rays ?
Cathode rays produce heat when incident on metals
Cathode rays travel in a straight line
Cathode rays do not deflect in electric field
Cathode rays produce fluorescence when they fall on certain materials.
When ultraviolet radiation is incident on a surface, no photoelectrons are emitted. If a second beam causes photoelectrons to be ejected, it may consist of
Radio waves
Infra-red waves
X-rays
Visible light rays
A deuteron strikes nucleus with subsequent emission of an alpha particle Identify the nucleus so produced
For a nuclear fusion process, the suitable nuclei are
Any nuclei
Heavy nuclei
Light nuclei
Nuclei lying in the middle of the periodic table
Solar energy is mainly caused due to
Gravitational contraction
Burning of hydrogen in the oxygen
Fission uranium present in the Sun
Fusion of protons during synthesis of heavier elements