Q.1
Which of the following statement is not correct ? [ AFMC 1999]
  • a)Infra-red photons have more energy than photons of visible light
  • b)Infra-red rays are invisiable but can cast shadows like visiable light
  • c)Photographic plates are sensitive to ultraviolet rays
  • d) Photographic plates are sensitive to infra-red rays.
Q.2
Bohr`s theroy was modified by ------- . [ AFMC 2003]
  • a) Rutherford and Soddy
  • b) Planck
  • c) Hund
  • d) Sommerfield
Q.3
)Atoms having different atomic number as well as different mass number but having same number of neutrons. --- [AFMC 2003]
  • a)isotopes
  • b) isobars
  • c)isotones
  • d)isodiaphers
Q.4
) The intensive property among the following is [ AFMC 2003]
  • a) energy
  • b) volume
  • c)entropy
  • d)temperature
Q.5
) the total energy of electron is 3.555 MeV. If its potential energy is zero, then its kinetic energy is ---- . [ AFMC 2000}
  • a)3.555 MeV
  • b) 3.5 MeV
  • c)3.545 MeV
  • d)3.045 Mev
Q.6
) The ratio of dimensions of Plank`s constant and that of the moment of interia is the dimension of ---- . [ AFMC 2007]
  • a) frenqucy
  • b) velocity
  • c) angular momentum
  • d) time
Q.7
) Kinetic energy of an electron accelerated in a potential difference of 100 V is{AFMC 1999}
  • a)
    ch-19_qn-61choice_img_no1.png
  • c)1.6 × 1021 J
  • b) 1.6 ×10⁻²⁹ J
  • d)1.6 × 10⁻¹⁷ J
Q.8
) Photoelectric effect shows{AFMC 2003}
  • a) wave nature of electrons
  • b) particle nature of light
  • c) both (a) and ( b)
  • d)none of the above
Q.9
) What is the ratio of the shortest wavelength of the Balmer series to the shortest wave length of the Lyman serises?{AFMC 2011}
  • a)4 : 1
  • b) 4 : 3
  • c)4 : 9
  • d)5 : 9
Q.10
) Fraction of tritium left after 150 years ( half life of tritium is 12.5 years) is{AFMC 2011}
  • a) 1 / 1024
  • b) 1 / 2048
  • c) 1 / 4096
  • d) 1 / 8192
Q.11
In the nuclear reaction , there is conservation of{AFMC 2000}
  • a)momentum
  • b) mass
  • c)energy
  • d)all of these
Q.12
) Rutherford's alpha particle experiment show that the atoms have{AFMC 2011}
  • a) electron
  • b) neutrons
  • c) nucleus
  • d) proton
Q.13
3) The velocity of an electron in the inner most orbit of an atom will be{AFMC 2002}
  • a)highest
  • b) lowest
  • c)mean
  • d)zero
Q.14
4) Which of the following is most unstable ?{AFMC 2005}
  • a) Electron
  • b) Proton
  • c)Neutron
  • d)alpha - particle
Q.15
5) The strength of the transverse magnetic field required to bend all photoelectrons within a circle of radius 50 cm when light of wavelength 4000A is incident on barium emitter is ( work function of barium is 2.5eV){AFMC 2004}
  • a) 5.2× 10⁻⁶ T
  • b) 4 × 10⁻⁴ T
  • c)4.0 × 10⁻⁶ T
  • d)5.2× 10⁻⁴ T
Q.16
6) After 2 hrs, 1/16 th of intial amount of certain radioactive isotope remains undecayd. The half life time of isotope is{AFMC 2005}
  • a) 15 min
  • b) 30 min
  • c) 45 min
  • d) 60 min
Q.17
7) If the energy of a hydrogen atom in nth orbit is En. then energy in nth orbit of a singly ionized helium atom will be{AFMC 2007}
  • a)4 En
  • b) En/4
  • c)2 En
  • d) En/2
Q.18
8) What is not released in nuclear disintegration?{AFMC 2009}
  • a) Electrons
  • b) Protons
  • c)Helium nucleus
  • d)gama rays
Q.19
9) When light of wavelength 300nm falls on a photoelectic emitter, photoelectrons are liberated. For another emitter, light of wavelength 600nm is sufficient for liberating photoelectrons. The ratio of the work function of the two emitters is{AFMC 2008}+
  • a) 1 : 2
  • b) 2 : 1
  • c)4 : 1
  • d) 1 : 4
Q.20
) Photoelectric effect shows{AFMC 2003}
  • a) wave nature of electron
  • b) particle nature of light
  • c) both (a) and (b)
  • d) none of these
Q.21
) Hard X-rays for the study of fractures in bones should have a minimum wavelength of 10-11 m. The accelrating voltage for electrons in X-ray machin should be{AFMC 2006}
  • a)< 124 kV
  • b) > 124 kV
  • c)between 60 kV and 70 kV
  • d)=100 kV
Q.22
) Alpha particles are [ AFMC 2003]
  • a) ionised helium atom
  • b) hydrogen atom
  • c)neutral atom
  • d)all of these
Q.23
) Half lives of two radioactive substances A and B are respectively 20 min and 40 min. Intially, the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is [ AFMC 2006]
  • a) 1 : 16
  • b) 4 : 1
  • c)1 : 4
  • d)1 : 1
Q.24
) In which of the the following system will be radius of the first orbit (n=1) be minimum? [ AFMC 2007]
  • a) Deuterium atom
  • b) hydrogen atom
  • c) Doubly ionized lithium
  • d) Singly ionised helium
Q.25
) The fussion of 235 U can be triggered by the absorption of a slow netron by a nucleus. Similarily, a slow proton can also be used.This statment is [ AFMC 2007]
  • a)correct
  • b) wrong
  • c)information is insufficient
  • d)none of the above.
Q.26
) Activity of radio active sample decreases to (1/3)rd of its original value in 3 days. Then in 9 days its actvity will become [ AFMC 2008]
  • a) (1/27) of the original value
  • b) (1/9) of the original value
  • c)(1/18) of the original value
  • d)(1/3) of the original value
Q.27
) A free neutron decays spontaneously into [ AFMC 2008]
  • a) a proton, an electron and anti neutrino
  • b) a proton, an electron and a neutrino
  • c)a proton and electron
  • d)a proton, and electron, a neutrino and an anti-neutrino
Q.28
) Electron cannot be constituent of the nucleus because [ AFMC 2010]
  • a) the electron is a negatively charged particle
  • b) the compton wave length of electron is larger than the size of nucleus
  • c) the mass of the electron is very small as compared to the mass of the neutron or proton
  • d) None of these
Q.29
) A free alpha particle and a free proton, which are seperated by a distance of 10-10 m are released. The K.E. of alpha particle when at infinite seperation is [ AFMC 2007]
  • a) 46 × 10⁻¹⁹ J
  • b) 23 × 10⁻¹⁹ J
  • c)36.8 × 10⁻¹⁹ J
  • d) 9.2 × 10⁻¹⁹ J
Q.30
) The specific charge of a proton is 9.6 × 107 C/kg . The sepcific charge of a alpha particle will be [ AFMC 2008]
  • a) 9.6 × 107 C/kg
  • b) 19.2 × 107 C/kg
  • c)4.8 × 107 C/kg
  • d)2.4 × 107 C/kg
0 h : 0 m : 1 s