Physics M.C.Q (1 Marks)

What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit(a) 27 : 25(b) 20 : 27(c) 20 : 25(d) 25 : 27

The curve of binding energy per nucleon as a function of atomic mass number has a sharp peak for helium nucleus. This implies that helium(a) Can easily be broken up(b) Is very stable (c) Can be used as fissionable material(d) Is radioactive

A nucleus is bombarded with a high speed neutron so that resulting nucleus is a radioactive one. This phenomenon is called(a) Artificial radioactivity(b) Fusion(c) Fission(d) Radioactivity

What is used as a moderator in a nuclear reactor(a) Water                                          (b) Graphite(c) Cadmium(d) Steel

Nuclear fusion is common to the pair(a) Thermonuclear reactor, uranium based nuclear reactor(b) Energy production in sun, uranium based nuclear reactor(c) Energy production in sun, hydrogen bomb(d) Disintegration of heavy nuclei, hydrogen bomb

The principle of controlled chain reaction is used in(a) Atomic energy reactor(b) Atom bomb(c) The core of sun(d) Artificial radioactivity

Heavy water is(a) Water at 4 ℃(b) Compound of deuterium and oxygen  (c) Compound of heavy oxygen and heavy hydrogen(d) Water, in which soap does not lather

Mark the correct statement(a) Nuclei of different elements can have the same number of neutrons(b) Every element has only two stable isotopes(c) Only one isotope of each element is stable(d) All isotopes of every element are radioactive

The binding energy of nucleus is a measure of its(a) Charge(b) Mass(c) Momentum(d) Stability

The kinetic energy of electron in the first Bohr orbit of the hydrogen atom is(a) – 6.5 eV(b) – 27.2 eV(c) 13.6 eV(d) – 13.6 eV

The kinetic energy of an electron revolving around a nucleus will be(a) Four times of P.E.(b) Double of P.E.(c) Equal to P.E.(d) Half of its P.E.

As the electron in Bohr orbit of Hydrogen atom passes from state n = 2 to n = 1, the kinetic energy K and potential energy U change as(a) K two-fold, U four-fold(b) K four-fold, U two-fold(c) K four-fold, U also four-fold  (d) K two-fold, U also two-fold

The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state(a) 0 eV(b) – 27.2 eV(c) 1 eV   (d) 2 eV

Which one of the relation is correct between time period and number of orbits while an electron is revolving in a orbit

In the spectrum of hydrogen atom, the ratio of the longest wavelength in Lyman series to the longest wavelength in the Balmer series is(a) 5/27(b) 1/93(c) 4/9(d) 3/2

After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is (a) 6000  (b) 9000(c) 3000  (d) 24000

The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant(a) 40 year, 0.9173/year(b) 90 year, 9.017/year(c) 80 year, 0.0173 year(d) None of these

The example of nuclear fusion is

Fission of nuclei is possible because the binding energy per nucleon in them(a) Increases with mass number at high mass numbers(b) Decreases with mass number at high mass numbers(c) Increases with mass number at low mass numbers(d) Decreases with mass number at low mass numbers

Assertion : Electron capture occurs more often than positron emission in heavy elements.
Reason    : Heavy elements exhibit radioactivity.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

Assertion : All the radioactive elements are ultimately converted in lead.
Reason     : All the elements above lead are unstable. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

The ratio of areas within the electron orbits for the first excited state to the ground state for hydrogen atom is(a) 16 : 1 (b) 18 : 1(c) 4 : 1    (d) 2 : 1

The colour of the second line of Balmer series is(a) Blue(b) Yellow(c) Red(d) Violet

The Bohr model of atoms             (a) Assumes that the angular momentum of electrons is quantized(b) Uses Einstein’s photo-electric equation(c) Predicts continuous emission spectra for atoms(d) Predicts the same emission spectra for all types of atoms

The shortest wavelength in the Lyman series of hydrogen spectrum is 912 Å corresponding to a photon energy of 13.6 eV. The shortest wavelength in the Balmer series is about(a) 3648 Å(b) 8208 Å(c) 1228 Å(d) 6566 Å

Which of the following is quantised according to Bohr’s theory of hydrogen atom(a) Linear momentum of electron(b) Angular momentum of electron(c) Linear velocity of electron(d) Angular velocity of electron

The ratio of the largest to shortest wavelengths in Lyman series of hydrogen spectra is

In a nuclear fission reaction(a) Two light nuclei combine to produce a heavier nucleus(b) A light nucleus bombarded by thermal neutrons breaks up(c) A heavy nucleus bombarded by thermal neutrons breaks up(d) A heavy nucleus breaks up by itself

Which of these is a fusion reaction