Practice Test

Q1) We have a source of red light and a blue light of same power. Then the red light gives photons per second Show Answer

Q2) The total energy E of the electron in a hydrogen atom is Show Answer

Q3) It is found experimentally that 13.6 eV energy is required to separate a hydrogen atom into a proton and an electron. The orbital radius is Show Answer

Q4) The wavelength of the second spectral lines in the Lyman series of the hydrogen spectrum is Show Answer

Q5) What is the shortest wavelength present in the Paschen series of the spectral lines ? Show Answer

Q6) A hydrogen atom initially in the ground level absorbs a photon which excites it to the n = 4 level. The wavelength of the photon is Show Answer

Q7) A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of spectral lines will be emitted. Show Answer

Q8) The reaction that indicates beta-minus decay is Show Answer

Q9) The reaction that indicates beta-plus decay is Show Answer

Q10) One of the following is not used as a moderator in a nuclear reactor Show Answer

Q11) When a hydrogen atom is raised from the ground state to an excited state Show Answer

Q12) According to Bohr's theory the radius of orbit described by principal quantum number n and atomic number Z is proportional to Show Answer

Q13) The ratio between kinetic energy and total energy of the electron of hydrogen atom, according to Bohr's model is Show Answer

Q14) In which of the following transitions will the wavelength be minimum ? Show Answer

Q15) The series limit wavelength of the Lyman series for hydrogen atom is give by Show Answer

Q16) Which of the following is true ? Show Answer

Q17) The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volts is equal to Show Answer

Q18) During a negative beta decay Show Answer

Q19) Pick out the statement which is true Show Answer

Q20) Fusion reaction takes place at high temperature because Show Answer

Q21) Statement 1 : Ionisation energy of atomic hydrogen is greater than atomic deuterium.
Statement 2 : Ionisation energy is proportional to reduced mass
Show Answer

Q22) Statement 1 : Nuclear energy is due to difference in sum of masses of component nucleons and the nucleus.
Statement 2 : Mass of nucleus is more than the sum of masses of component nucleons.
Show Answer

Q23) What are number of nuclei of C, when number of nuclei of A and B are equal ? Show Answer

Q24) At what time rate of disintegration of A and B are equal ? Show Answer

Q25) Which of the following process represents a gamma-decay ? Show Answer

Q26) The mass defect for the nucleus of helium is 0.0303 amu. What is the binding energy per nucleon for helium in MeV ? Show Answer

Q27) The masses of neutron and proton are 1.0087 amu and 1.0073 amu respectively. If the neutrons and protons combine to form a helium nucleus ( alpha particles ) of mass 4.0015 amu, the binding energy of the helium nucleus will be ( 1 amu = 931 MeV) Show Answer

Q28) Statement 1 : In radioactive disintegration electron is emitted by nucleus.
Statement 2 : Electrons are always present inside nucleus.
Show Answer

Q29) What is the initial state of electron in hydrogen atom ? Show Answer

Q30) In final state : Show Answer

Q31) As the electron pimps, the ratio of its energy in the final state to initial state is Show Answer

Q32) The mass number of a nucleus is Show Answer

Q33) According to classical electromagnetic theory, the electron in an atom will move along a Show Answer

Q34) The ratio of the speed of an electron in the ground state in Bohr's first orbit of hydrogen atom to velocity of light in air is Show Answer

Q35) The energy required to remove an electron in a hydrogen atom from the state corresponding to n = 10 is Show Answer

Q36) The energy of the electron in the ground state of Hydrogen atom is -13.6 eV. The energy of the electron in the first excited state is Show Answer

Q37) The energy of an electron in the excited hydrogen atom is -3.4 eV. Then according to Bohr's theory, the angular momentum of the electron in that excited state is Show Answer

Q38) For an electron in the third orbit of Bohr Hydrogen atom, the moment of linear momentum is Show Answer

Q39) The energy of an excited hydrogen atom is -3.4 eV. The principal quantum number of the orbit is Show Answer

Q40) In a hydrogen atom, the total energy of an electron in a given orbit is -1.5 eV. The potential energy in the same oporbit is Show Answer

Q41) According to Bohr's atom model, the diameter of the first orbit of an electron in a hydrogen atom is Show Answer

Q42) For an hydrogen atom, the ratio of the area of the orbit of the first excited state of electron to the area of the orbit of the ground level is Show Answer

Q43) According to Bohr's theory, the energy of radiation emitted in the transition from the third excited state to the first excited state for a hydrogen atom is excited state for Show Answer

Q44) The ratio of the angular momenta of an electron in 13.6 eV the second and fifth Bohr orbit is Show Answer

Q45) When the orbital electron of a hydrogen atom goes from the ground state to a higher energy state, its velocity is reduced to one third of its initial value. If the radius of its orbit in the ground state is R, then the radius of the new orbit will be Show Answer

Q46) The ratio of the areas of the circular orbits of an electron in the ground state to that for the first excited state of an electron in the hydrogen atom is Show Answer

Q47) In Bohr atom model, the ratio of the periods of revolution of an electron in the orbits of first excited state and ground state is Show Answer

Q48) The ground state energy of hydrogen atom is - 13.6 eV. The energy needed to ionise H-atom from its second excited state is Show Answer

Q49) The energy of a hydrogen atom in the ground state is -13.6 eV. What is the energy required to raise an electron from the first orbit to the second orbit? Show Answer

Q50) If r is the radius of the orbit of the electron in the hydrogen atom, then its angular momentum is proportional to Show Answer

Q51) The ground state energy of hydrogen atom is - 13.6 eV. What is the P. E. of the electron in this state? Show Answer

Q52) The total energy of an electron in the first excited state of hydrogen atom is about-3.4 eV. What is its K.E. in this state? Show Answer

Q53) The minimum excitation potential of Bohr's first orbit in hydrogen atom Show Answer

Q54) The ratio of the areas of the electron orbits for the second excited state to the first excited state for the hydrogen atom is Show Answer

Q55) Which is the wrong statement from the following?
When an electron moves in the third Bohr orbit of a hydrogen atom. Show Answer

Q56) The momentum of a photon is p. The corresponding wavelength is Show Answer

Q57) What is the ratio of the energies of an hydrogen atom, when it is in the third and second excited states? Show Answer

Q58) The total energy of an electron in the first excited state of hydrogen atom is -3.4 eV. What are the values of its K.E. and P.E. in this state? Show Answer

Q59) When an orbital electron of the hydrogen atom is raised from the ground state to a higher energy state, its orbital speed reduces to half its initial value. If the radius of the initial electron orbit is r, then the new orbital radius will be Show Answer

Q60) If the electron in a hydrogen atom moves from ground state orbit to 5th orbit, then the potential energy of the system Show Answer

Q61) What is the minimum energy (in eV) required to remove an electron from the ground state level of a doubly ionized Li atom (Z = 3)? (Based on Bohr model) Show Answer

Q62) What is the radius of the second orbit of helium atom, on the basis of Bohr's atom model? Show Answer

Q63) For an electron moving in nth orbit of H-atom the angular velocity is proportional to Show Answer

Q64) When the electron revolving in Bohr orbits of hydrogen atom goes from state n = 2 to n = 1, the kinetic energy K and potential energy U will change as Show Answer

Q65) What is the ratio of the speed of the electrons in the ground state of hydrogen atom to the speed of light in vacuum? Show Answer

Q66) In Bohr model of hydrogen atom, the force acting on the electron due to the nucleus depends upon the principal quantum number as Show Answer

Q67) What is the approximate value of the quantum number n for the circular orbit of hydrogen 0.0001 mm in diameter? Show Answer

Q68) The energy of a hydrogen atom in its ground state is -13.6 eV. What is the quantum number of the orbit corresponding to the energy level of -0.85 eV? Show Answer

Q69) Hydrogen atoms in the ground state are excited by monochromatic radiation photons of energy 12.1 eV. To which orbit the electron will be lifted, if a hydrogen atom absorbs the photon? Show Answer

Q70) The electron in the hydrogen atom jumps from the second orbit to the fourth orbit after absorbing photon. In this process Show Answer

Q71) The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which one of the following statements is true? Show Answer

Q72) Which one of the following atoms has the highest ionisation potential? Show Answer

Q73) What is the moment of inertia of the electron moving in the second Bohr orbit of a hydrogen atom? Show Answer

Q74) How will you express, the energy of the electron in the nth orbit, in terms of the Rydberg constant, planck's constant and the velocity of light? Show Answer

Q75) For the hydrogen atom, the energy of radiation emitted in the transition from 4th excited state to 2nd excited state, according to Bohr's theory is Show Answer

Q76) The magnitude of the P.E. of the electron in the first orbit of the Bohr's atom is E. What is its K.E.? Show Answer

Q77) The orbital frequency of an electron in a hydrogen atom is proportional to (n is the principal quantum no.) Show Answer

Q78) In Bohr's orbit, kinetic energy of an electron in the nth orbit of an atom in terms of angular momentum is proportional to Show Answer

Q79) The ionisation energy of Hydrogen atom is 13.6 eV. What is the ionisation energy of He? Show Answer

Q80) A hydrogen atom in its ground state absorbs 10.2 eV of energy. What is the increase in its orbital angular momentum? Show Answer

Q81) The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. In which one of the following transitions, infrared radiations will be obtained? Show Answer

Q82) An electron accelerated through a potential difference of 4.9 V collides with a mercury atom and transfers it to the first excited state. What is the wavelength of radiation emitted in the transition of the mercury atom from its excited state to its normal state? Show Answer

Q83) What is the orbital acceleration of the electron in the first Bohr orbit of hydrogen atom? Show Answer

Q84) If r, v and E denote the radius of the orbit, speed of the electron and the total energy of the electron respectively in the Bohr model of hydrogen atom, then which of the following quantity is directly proportional to the quantum number n? Show Answer

Q85) The ionization energy of the electron in the hydrogen atom in its ground state is 13.6 eV. The atoms are excited to higher energy levels to emit radiations consisting of 6 wavelengths. Maximum wavelength of emitted radiation corresponds to the transition between Show Answer

Q86) An energy of 25.6 eV is required to remove one of the electrons from a neutral helium atom. What is the energy (in eV) required to remove both the electrons from a neutral helium atom? Show Answer

Q87) Which one of the following atoms has the lowest ionization potential? Show Answer

Q88) Consider the electron in a singly ionised helium atom and in a hydrogen atom. What is the ratio of their accelerations, if both of them are in the ground state? Show Answer

Q89) If the P.E. of a Bohr's hydrogen atom in the ground state is zero, then its total energy in the first excited state will be Show Answer

Q90) As per Bohr atom model, the minimum energy (in eV) required to remove an electron from the ground state of doubly ionised Lithium atom (Z = 3) is Show Answer

Q91) If elements with principal quantum number n > 4 were not allowed in nature, the number of possible elements would be Show Answer

Q92) Which one is the wrong option from the following in the Bohr model of the hydrogen atom? Show Answer

Q93) A hydrogen-like atom of atomic number Z is in an excited state of quantum number n = 6. This excited atom makes a transition to the first excited state by successively emitting 2 photons of energies 10.2 eV and 17.00 eV respectively. What is the value of Z, if the ionisation energy of hydrogen is 13.6 eV? Show Answer

Q94) According to Bohr model the magnetic field at the centre (at the nucleus) of a hydrogen atom due to the motion of the electron in nth orbit is proportional to Show Answer

Q95) Suppose that the mass of an electron is doubled. How will it affect the Rydberg constant? Show Answer

Q96) An electron jumps from the fourth orbit to the second orbit of Hydrogen atom. The wave number of the radiations emitted by the electron is Show Answer

Q97) The ratio of the maximum to minimum wavelengths in Balmer series is Show Answer

Q98) In Bohr's model of a hydrogen atom, an electron jumps from the fifth orbit to the second orbit. Which line of the Balmer series is produced in this transition? Show Answer

Q99) The maximum wavelength of Lyman series is Show Answer

Q100) The maximum number of photons emitted when an electron jumps from an energy level n = 5 to n = 1 is Show Answer

Q101) The ratio of the frequencies of the long wavelength limits of the Lyman and Balmer series of hydrogen is Show Answer

Q102) What is the ratio of the series limit of the Pfund series to that of the Lyman series in the emission spectrum of hydrogen? Show Answer

Q103) When an electron is an excited hydrogen atom, jumps from n = 4 to n = 2 level, green light is emitted. Which colour of light will be observed, if the electron jumps from n = 6 to n = 2? Show Answer

Q104) The wavelength of a line in a spectrum is inversely proportional to Show Answer

Q105) Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation photons of energy 12.1 eV. How many spectral lines will be emitted by the hydrogen atom according to Bohr's theory? Show Answer

Q106) In a hydrogen atom, ultraviolet radiations are emitted when the electron jumps from Show Answer

Q107) In a hydrogen atom, infrared radiations are obtained in the transition of an electron from Show Answer

Q108) What is the ratio of the wavelengths of radiation emitted when an electron in the hydrogen atom jumps from the fourth orbit to the second orbit and from the third orbit to the second orbit? Show Answer

Q109) The frequency of series limit of Balmer series of hydrogen atom in terms of Rydberg constant R and velocity of light (C) is Show Answer

Q110) What is the number of spectral lines in a hydrogen V spectrum? Show Answer

Q111) Which one of the following phenomena suggests the presence of electron energy levels in atoms? Show Answer

Q112) In hydrogen spectrum, as we go from Lyman series to Pfund series, the number of spectral lines Show Answer

Q113) A photon beam containing photons of various energies is passed through a sample of hydrogen like atoms, all the atoms being in the ground state. It was found that there were 4 dark lines in the absorption spectrum. What is the maximum number of lines that will be produced in the emission spectrum? Show Answer

Q114) The absorption transitions between the first and the fourth energy states of hydrogen atom are 3. The emission transitions between these states will be Show Answer

Q115) The ratio of longest wavelength and the shortest wavelength observed in the five spectral series of emission spectrum of hydrogen is Show Answer

Q116) When an electron jumps from n = 4 to n = 2 orbit in a hydrogen atom, we get, Show Answer

Q117) If an electron in hydrogen atom jumps from an orbit of level n = 3 to an orbit of level n = 2, the emitted radiation has a frequency (R = Rydberg's constant, C = velocity of light) Show Answer

Q118) Which of the following transitions in hydrogen atoms emit photons of highest frequency? Show Answer

Q119) Wavelengths of some of the lines emitted by H atoms are given below. Which line belongs to Lyman series? Show Answer

Q120) The longest wavelength in the ultraviolet region of the hydrogen spectrum is 120 nm. What is the smallest wavelength in the infrared region of the hydrogen spectrum? Show Answer

Q121) The force of repulsion between two electrons kept at a distance of 1 m is F. If m is the mass of the electron, h is the Planck's constant and C is the velocity of light, then the Rydberg's constant is Show Answer

Q122) Which one of the following statements is true for nuclear forces? Show Answer

Q123) The mass number of He is 4 and that for sulphur is 32. What is the ratio of the radius of the sulphur nuclei to that of the helium nuclei? Show Answer

Q124) The volume of the nucleus of an atom of an element of mass number A is proportional to Show Answer

Q125) What is the ratio of the nuclear radii of two elements with mass numbers 27 and 125? Show Answer

Q126) Which one of the following nuclear reaction is NOT possible? Show Answer

Q127) Let u denote one atomic mass unit. One atom of an element of mass number A has mass exactly equal to Au. Show Answer

Q128) Which one of the following has the highest neutron to proton ratio? Show Answer

Q129) Which one of the following is a possible nuclear reaction? Show Answer

Q130) For a Uranium nucleus, how does its mass vary with volume (V)? Show Answer

Q131) Which one of the following statements/reactions is correct? Show Answer

Q132) The mass density of a nucleus varies with mass number A as Show Answer

Q133) A nucleus ruptures into two nuclear parts, which have their velocity ratio equal to 2: 1. What will be the ratio of their nuclear size (or nuclear radii)? Show Answer

Q134) What is the ratio of the volume of the atom to the volume occupied by its nucleus? Show Answer

Q135) A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio 8: 1. What is the ratio of the radii of the fragments? Show Answer

Q136) Which one is the correct equation? Show Answer

Q137) The mass defect in a particular nuclear reaction is 0.3 gram. What is the amount of energy liberated in the nuclear reaction in units of kilowatt hour? Show Answer

Q138) How much energy will be released, if a proton and an antiproton come very close to each other and annihilate? Show Answer

Q139) Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is Show Answer

Q140) In nucleus fission process, energy is released because Show Answer

Q141) Which of the following are suitable for the fusion process? Show Answer

Q142) Fission of nuclei is possible because the binding energy per nucleon in them Show Answer

Q143) Thermal neutrons are those which Show Answer

Q144) A chain reaction becomes continuous due to Show Answer

Q145) When two deuterium nuclei fuse together to form a tritium nuclei, we get a Show Answer

Q146) Heavy water is Show Answer

Q147) For an atomic reactor being critical, the ratio (r) of the average number of neutrons produced and used in chain reaction Show Answer

Q148) The operation of a nuclear reactor is said to be critical, if the multiplication factor (k) has a value. Show Answer

Q149) Fast neutrons can easily be slowed down by Show Answer

Q150) Which one of the following statement(s) is correct? Show Answer

Q151) From the following equations pick out the possible nuclear fusion reaction: Show Answer

Q152) During a negative beta decay Show Answer

Q153) Which is the most penetrating radiation out of the following? Show Answer

Q154) The activity of a radioactive sample Show Answer

Q155) When a radioactive element emits an a particle, its position in the periodic table is Show Answer

Q156) The 'rad' is the correct unit used to report the measurement of Show Answer

Q157) In a gamma ray emission from a nucleus Show Answer

Q158) Which one of the following radiations has the least wavelength? Show Answer

Q159) Which one of the following cannot be emitted by radioactive substances during their decay? Show Answer

Q160) Which one of the following is a correct statement? Show Answer

Q161) Beta rays emitted by a radioactive material are Show Answer

Q162) In an alpha decay, the neutron to proton ratio Show Answer

Q163) The nuclei of which one of the following pairs of nuclei are isotones? Show Answer

Q164) What is the percentage of the initial number of active nuclei decaying during one mean life of a radioactive material? [e = 2.71] Show Answer

Q165) A counter gives a count of 320 counts/minute for a radioactive source. After 75 minutes, the counter shows a count rate of 40 counts/minute. What is the half life period of the source? Show Answer

Q166) The half life of a radio isotope is 3h. The mass of the isotope at time t = 0 is 160 gram. What is the mass of the isotope left after 15 h? Show Answer

Q167) A box contains a radioactive material of mass 14.58 gram at time t = 0. What is the mass of the element left in the box after a time of 2 mean lives? (Take e = 2.7) Show Answer

Q168) N atoms of a radioactive element emit n alpha particles per second. What is the half life of the element? Show Answer

Q169) For a radioactive substance, how much of its initial quantity will disintegrate in its mean-life time? Show Answer

Q170) 99% quantity of a radioactive substance decays between Show Answer

Q171) A radioactive substance has an average life (mean life) of 5 hours. Then in this time Show Answer

Q172) The half life of a radioactive substance is 10 year. How long will it take to reduce to one fourth of its original amount and what is the value of its decay constant? Show Answer

Q173) The mean life of a radioactive sample is 100 second. What is its half life? Show Answer

Q174) In a sample of a radioactive material, what fraction of the initial number of active nuclei will remain undisintegrated after half of a half-life of the sample? Show Answer

Q175) Suppose that a radioactive substance disintegrates completely in 10 days. Each day it disintegrates at a rate twice the previous day. Then after nine days the percentage of the material left to be disintegrated is Show Answer

Q176) Half life period and mean life period of a radioactive element are Show Answer

Q177) Starting with a sample of pure 66Cu, 7/8 of the sample are decays into Zn in 15 minute. The corresponding half-life is Show Answer

Q178) A freshly prepared radioactive source of half-life 2 hour emits radiation of intensity which is 64 times the permissible safe level. What is the minimum time after which it would be possible to work safely with this source? Show Answer

Q179) The half-life of radium is 1600 year. The fraction of a sample of radium that would remain after 6400 year is Show Answer

Q180) The half life of a radioactive material is 3 h. If the initial amount is 300 g, then after 18 h, the remaining amount will be Show Answer

Q181) Half-life of a radioactive substance is 12.5 h and its mass is 256 g. After what time, the amount of the remaining substance is 1 g? Show Answer

Q182) A sample of radioactive element has a mass of 10 g at an instant t = 0. What is the approximate mass of this element in the sample after two mean lives? Show Answer

Q183) A radioactive sample with a half life of 1 month has the label: "Activity = 4 micro curie on 11-12-2013". What will be its activity after two months? Show Answer

Q184) The activity of a radioactive sample is measured as 9750 counts per minute at t = 0 and as 975 counts per minute at t = 5 minutes. What is the approximate decay constant of the sample? Show Answer

Q185) The half life period of a radioactive element X is the same as the mean life time of another radioactive element Y. Initially both of them have the same number of radioactive atoms. Then Show Answer

Q186) The half life of a radioactive substance is 4 days. The probability that a nucleus will decay into two half lives is Show Answer

Q187) Half-lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially, the samples of A and B have equal number of nuclei. After 80 min the ratio of the remaining number of A and B nuclei will be Show Answer

Q188) If 8 g of a radioactive substance decays into 0.5 g in 1 h, then the half-life of the substance is Show Answer

Q189) The linear momentum of an electron in Bohr orbit of H-atom (principal quantum number n) is proportional to Show Answer

Q190) The nuclei having the same number of protons but different number of neutrons are called Show Answer

Q191) In Bohr's theory of Hydrogen atom, the electron jumps from higher orbit 'n' to lower orbit 'p'. The wavelength will be minimum for the transition Show Answer

Q192) When an electron in a hydrogen atom revolves in stationary orbit, it Show Answer

Q193) A radioactive element has rate of disintegration 10,000 disintegrations per minute at a particular instant. After four minute it becomes 2500 disintegrations per minute. The decay constant per minute is Show Answer