Bohr’s Atomic Model MCQs
Sir Neil Bohr studied the hydrogen atom and describes the most modern structure of atom in his postulates. He suggested that the negatively charged electron revolves around the positively charged nucleus in circular orbit due to presence of electrostatic force of attraction between the positively charged nucleus and negatively charged electrons. The postulates given by Bohr’s are as follows.
Postulate-1) In hydrogen atom, an electron revolves in circular orbit round the nucleus. The necessary centripetal force of attraction between the positively charged nucleus& negatively charged electrons.
Postulate–2) The electron revolve around nucleus only in those restricted orbits, in which angular momentum of electron is equal to an integral multiple of h/2π Where h is Planck’s constant.
Postulate-3): An electron radiates photon energy when it jumps from higher energy orbit to lower energy orbit which is equal to the difference between the energies of the electron in two orbits.
It is also found that the radius of nth Bohr’s orbit is directly proportional to the square of principal quantum number.
∴ r ∝ n2
Q.1) The centripetal force required for motion of electron around nucleus is provided by…..
a) Gravitational force
b) Electrostatic force
c) Nuclear force
d) Weak Nuclear force
Q.2) According to Bohr’s atomic model, the angular momentum of electron in a given orbit should be multiple of………..
Q.3) During transition of electrons from orbits of higher energy to the orbit of lower energy, energy is…….
a) absorbed
b) radiated
c) either ‘a’ or b’
d) none of these.
Q.4) The radius of Bohr’s orbit is……..
a) directly proportional to principal quantum number
b) directly proportional to square of principal quantum number
a) inversely proportional to principal quantum number
d) inversely proportional to square of principal quantum number
Q.5) The difference in angular momentum of revolving electron in 3rd to that of 6th orbit is…..
Q.6) Ratio of radius of 4th Bohr’s orbit to 7th orbit is….
a) 4:7
b) 7:4
c) 16:49
d) 49:16
Q.7) If frequency required for transition of electron from 2nd orbit to 5th orbit is 4×1015 Hz, the energy absorbed during the transition is…..
a) 16.5 eV
b) 26.5 eV
c) 16.5 J
d) 26.5 J
Q.8) Which among the following is not correct for electron in Bohr’s orbit?
a) Electrostatic force between nucleus and electron provides necessary centripetal force
b) Angular momentum of electron is an integral multiple of h/2π
c) Energy is absorbed during transition of electron from higher to lower orbit.
d) Radius of Bohr’s orbit is directly proportional to square of principal quantum number
Q.9) Angular momentum of electron in 3rd Bohr’s orbit is….
Answers:
Q.1) b) Electrostatic force
Q.2) d) h/2π
Q.3) b) radiated
Q.4) b) directly proportional to square of principal quantum number
Q.5) d) 1.5 h/2π
Q.6) c) 16:49
Q.7) a) 16.5 eV
Q.8) c) Energy is absorbed during transition of electron from higher to lower orbit.
Q.9) c) 3.1× 10-34 kg.m2/s
