Practice Test


Q1) The total energy E of the electron in a hydrogen atom is Show Answer


Q2) 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


Q3) The wavelength of the second spectral lines in the Lyman series of the hydrogen spectrum is Show Answer


Q4) What is the shortest wavelength present in the Paschen series of the spectral lines ? Show Answer


Q5) 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


Q6) 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


Q7) The reaction that indicates beta-minus decay is Show Answer


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


Q9) One of the following is not used as a moderator in a nuclear reactor Show Answer


Q10) A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to 3.125% ? 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) The ionisation energy of a hydrogen- like atom is 9 Rydberg. The radius of first orbit of this atom, as compared to the radius of first orbit of hydrogen atom, will be Show Answer


Q17) Which of the following is true ? Show Answer


Q18) The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volts is equal to Show Answer


Q19) During a negative beta decay Show Answer


Q20) Pick out the statement which is true Show Answer


Q21) Fusion reaction takes place at high temperature because Show Answer


Q22) Statement 1 : Ionisation energy of atomic hydrogen is greater than atomic deuterium.
Statement 2 : Ionisation energy is proportional to reduced mass
Show Answer


Q23) 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


Q24) What are number of nuclei of C, when number of nuclei of A and B are equal ? Show Answer


Q25) At what time rate of disintegration of A and B are equal ? Show Answer


Q26) Which of the following process represents a gamma-decay ? Show Answer


Q27) 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


Q28) 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


Q29) In final state : Show Answer


Q30) As the electron pimps, the ratio of its energy in the final state to initial state is Show Answer


Q31) The mass number of a nucleus is Show Answer


Q32) If in nature there may not be an element for which the principal quantum number n > 4, then the total possible number of elements will be Show Answer


Q33) In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly proportional to (n = principle quantum number) Show Answer


Q34) In the following atoms and moleculates for the transition from n= 2 to n = 1, the spectral line of minimum wavelength will be produced by Show Answer


Q35) The Lyman series of hydrogen spectrum lies in the region Show Answer


Q36) The size of an atom is of the order of Show Answer


Q37) Which one of the series of hydrogen spectrum is in the visible region Show Answer


Q38) Which of the following is true Show Answer


Q39) The energy required to knock out the electron in the third orbit of a hydrogen atom is equal to Show Answer


Q40) In a beryllium atom, if a0 be the radius of the first orbit, then the radius of the second orbit will be in general Show Answer


Q41) The ionization potential for second He electron is Show Answer


Q42) The energy required to remove an electron in a hydrogen atom from n=10 state is Show Answer


Q43) Every series of hydrogen spectrum has an upper and lower limit in wavelength. The spectral series which has an upper limit of wavelength equal to 18752 Å is Show Answer


Q44) The kinetic energy of the electron in an orbit of radius r in hydrogen atom is (e = electronic charge) Show Answer


Q45) Ionization potential of hydrogen atom is 13.6 V. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atoms according to Bohr's theory will be
Show Answer


Q46) The ratio of the energies of the hydrogen atom in its first to second excited state is Show Answer


Q47) The ionisation potential of hydrogen atom is 13.6 volt. The energy required to remove an electron in the n = 2 state of the hydrogen atom is Show Answer


Q48) The ionisation energy of 10 times ionised sodium atom is Show Answer


Q49) The radius of electron's second stationary orbit in Bohr's atom is R. The radius of the third orbit will be Show Answer


Q50) Which of the following particles are constituents of the nucleus Show Answer


Q51) The particles which can be added to the nucleus of an atom without changing its chemical properties are called Show Answer


Q52) The neutron was discovered by Show Answer


Q53) The mass number of a nucleus is Show Answer


Q54) The energy equivalent of 1 kilogram of matter is about Show Answer


Q55) Nuclear binding energy is equivalent to Show Answer


Q56) If the binding energy of the deutrium is 2.23 MeV.
The mass defect given in a.m.u. is
Show Answer


Q57) Which of the following has the mass closest in value to that of the positron Show Answer


Q58) Size of nucleus is of the order of Show Answer


Q59) For effective nuclear forces, the distance should be Show Answer


Q60) The masses of neutron and proton are 1.0087 a.m.u. and 1.0073 a.m.u. respectively. If the neutrons and protons combine to form a helium nucleus (alpha particles) of mass 4.0015 a.m.u. The binding energy of the helium nucleus will be (1 a.m.u.= 931 MeV) Show Answer


Q61) The mass defect for the nucleus of helium is 0.0303 a.m.u. What is the binding energy per nucleon for helium in MeV Show Answer


Q62) Atomic power station at Tarapore has a generating capacity of 200 MW. The energy generated in a day by this station is Show Answer


Q63) One microgram of matter converted into energy will give Show Answer


Q64) The average binding energy per nucleon in the nucleus of an atom is approximately Show Answer


Q65) Binding energy of a nucleus is Show Answer


Q66) Which of the following pairs is an isobar Show Answer


Q67) Equivalent energy of mass equal to 1 a.m.u. is Show Answer


Q68) The mass number of a nucleus is equal to the number of Show Answer


Q69) The rest energy of an electron is Show Answer


Q70) Outside a nucleus Show Answer


Q71) Nucleus of an atom whose atomic mass is 24 consists of Show Answer


Q72) The mass of a neutron is the same as that of Show Answer


Q73) The mass defect per nucleon is called Show Answer


Q74) The element used for radioactive carbon dating for more than 56000 yr is Show Answer


Q75) First Bohr radius of an atom with Z= 82 is R. Radius of its third orbit is Show Answer


Q76) Which is the correct expression for half-life Show Answer


Q77) The radius of a nucleus with atomic mass number 7 is 2fermi. Find the radius of nucleus with atomic number 189. Show Answer


Q78) In Bohr’s model of hydrogen atom, which of the following pairs of quantities are quantized? Show Answer


Q79) The ratio of minimum wavelength of Lyman and Balmer series will be Show Answer


Q80) The ionisation potential of hydrogen atom is −13.6 eV. An electron in the ground state of a hydrogen
atoms absorbs a photon of energy 12.75 eV. How many different spectral line can one expect when the
electron make a downward transition? Show Answer


Q81) Ionization potential of hydrogen atom is13.6 eV. Hydrogen atoms in the ground state are excited by
monochromatic radiation of photon energy 12.1 eV. According to Bohr’s theory, the spectral lines emitted
by hydrogen will be Show Answer


Q82) The ratio of areas of the electron orbits for the first excited state and the ground state for the hydrogen
atom is Show Answer


Q83) In Raman effect, Stokes’ lines are spectral lines having Show Answer


Q84) What is the difference of angular momenta of an electron in two consecutive orbits in hydrogen atom? Show Answer


Q85) The Kinetic energy of the electron in an orbit of radius r in hydrogen atom is (e=electronic charge) Show Answer


Q86) Let the PE of hydrogen atom in the ground state be zero. Then its total energy in the first excited state will be Show Answer


Q87) photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is 10.2 eV. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of 15n eV. What will be observed by the detector? Show Answer


Q88) When a hydrogen atom is bombared, the atom is excited to then n=4 state. The energy released, when the atom goes from n=4 state to the ground state is Show Answer


Q89) In the Bohr model of the hydrogen atom, let R,V and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively. Which of the following quantities is proportional to quantum number n? Show Answer


Q90) For ionising an excited hydrogen atom, the energy required (in eV) will be Show Answer


Q91) The angular momentum of electron in hydrogen atom is proportional to Show Answer


Q92) For an electron in the second orbit of Bohr’s hydrogen atom, the moment of linear momentum is Show Answer


Q93) If the shortest wavelength in the Lyman series is 911.6 Å, the longest wavelength in the same series will be Show Answer


Q94) According to Bohr’s atomic model, the relation between principal quantum number(n) and radius of orbit(r) is Show Answer


Q95) The atomic number and the mass number of an atom remains unchanged when it emits Show Answer


Q96) The Rydberg constant R for hydrogen is Show Answer


Q97) Which of the following transition in Balmer series for hydrogen will have longest wavelength? Show Answer


Q98) Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are exicted by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atom according to Bohr’s theory will be Show Answer


Q99) The ratio of the frequencies of the long wavelength limits of the Lyman and Balmer series of hydrogen is Show Answer


Q100) The ratio of kinetic energy and the total energy of the electron in the nth quantum state of Bohr’s atomic model of hydrogen atom is Show Answer


Q101) The ratio of minimum to maximum wavelength in Balmer series is Show Answer


Q102) Solar spectrum is an example for Show Answer


Q103) Assuming f to be frequency of first line in Balmer series, the frequency of the immediate next( i.e, second) line is Show Answer


Q104) The transition from the state n =4 to n=3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from Show Answer


Q105) An electron of charge e moves with a constant speed v along a circle of radius r, its magnetic moment will be Show Answer


Q106) The angular momentum (L) of an electron moving in a stable orbit around nucleus is Show Answer


Q107) Mercury vapour lamp gives Show Answer


Q108) The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is Show Answer


Q109) Excitation energy of a hydrogen like atom in its first excitation state is 40.8 eV. Energy needed to remove the electron from the ion in ground state is Show Answer


Q110) The ionisation potential of hydrogen atom is 13.6 eV. The energy required to remove an electron from the second orbit of hydrogen will be Show Answer


Q111) A neon sign does not produce Show Answer


Q112) If a is radius of first Bohr orbit in hydrogen atom, the radius of the third orbit is Show Answer


Q113) In the Bohr’s model of the hydrogen atom, the lowest orbit corresponds to Show Answer


Q114) In the spectrum of hydrogen atom, the ratio of the longest wavelength in Lyman series to the longest wavelength in the Balmer series is Show Answer


Q115) The colour of the second line of Balmer series is Show Answer


Q116) Continuous emission spectrum is produced by Show Answer


Q117) The total energy of an electron in the first excited state of hydrogen is about −3.4eV. Its kinetic energy in this state is Show Answer


Q118) What is the maximum wavelength of light emitted in Lyman series by hydrogen atom? Show Answer


Q119) When hydrogen atom is in its first excited level, its radius is how many times its ground state radius? Show Answer


Q120) If the electron in hydrogen atom jumps from the third to second orbit, the wavelength of the emitted radiation in terms of Rydberg constant R is given by Show Answer


Q121) The shortest wavelength in Lyman series is 91.2 nm. The longest wavelength of the series is Show Answer


Q122) In a hydrogen atom, the electron in a given orbit has total energy −1.5 eV. The potential energy is Show Answer


Q123) In an inelastic collision an electron excites a hydrogen atom from its ground state to a M-shell state. A second electron collides instantaneously with the excited hydrogen atom in the M-state and ionizes it.At least how much energy the second electron transfers to the atom in the M-state? Show Answer


Q124) The series limit wavelength of the Lyman series for the hydrogen atom is given by Show Answer


Q125) An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transition. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transition. The ratio of the velocities of the electron in these two orbits is Show Answer


Q126) The ionization energy of hydrogen atom is 13.6eV. Following Bohr’s theory, the energy corresponding to a transition between 3rd and 4th orbit is Show Answer


Q127) For hydrogen atom electron in n th Bohr orbit, the ratio of radius of orbit to its de-Broglie wavelength is Show Answer


Q128) The energy of an electron in an excited hydrogen atom is −3.4 eV. Its angular momentum is Show Answer


Q129) The first excitation potential of a given atom is 10.2 V. Then ionisation potential must be Show Answer


Q130) The ionisation energy of 10 time ionised sodium atom is Show Answer


Q131) The spin-orbit interaction has no effect in the level of the hydrogen atom Show Answer


Q132) Pick out the unmatched pair from the following Show Answer


Q133) The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 Å. The wavelength of the second spectral line in the Balmer series of singly ionized helium atom is Show Answer


Q134) What is the radius of Iodine atom? (Atomic no.53, mass no.126) Show Answer


Q135) Hydrogen atom excites energy level from fundamental state to n=3. Number of spectrum lines, according to Bohr, is Show Answer


Q136) If elements with principal quantum number n>4 not allowed in nature, the number of possible elements would be Show Answer


Q137) Ionisation potential of hydrogen atom is 13.6 eV. The least energy of photon of Balmer series is Show Answer


Q138) A count rate metre shows a count of 240 per minute from a given radioactive source later the metre shows
a count rate 0f 30 min
. The half-life of the source is
Show Answer


Q139) The first excited state of hydrogen atoms is 10.2 eV above its ground state. The temperature needed to excite hydrogen atoms to first excited level, is Show Answer


Q140) In an atom, the two electrons move round the nucleus in circular orbits of radii R and 4R. The ratio of the times taken by them to complete one revolution is Show Answer


Q141) The orbital frequency of an electron in the hydrogen atom is proportional to Show Answer


Q142) Which of the following isotopes is normally fissionable Show Answer


Q143) When the wave of hydrogen atom comes from infinity into the first orbit then the value of wave number is Show Answer


Q144) Half-life of radioactive substance is 3.20 h. What is the time taken for a 75% of substance to be used?
Show Answer


Q145) In hydrogen atom, when electron jumps from second to first orbit, then energy emitted is Show Answer


Q146) The volume of a nucleus is directly proportional to Show Answer


Q147) Solar energy is mainly cause due to Show Answer


Q148) The ratio of minimum to maximum wavelength in Balmar series is Show Answer


Q149) Half life of a radioactive element is 10 days. The time during which quantity remains 1/10 of initial mass will be Show Answer


Q150) In beta decay Show Answer


Q151) The first line of Balmer series has wavelength 6563 Å. What will be the wavelength of the first member of Lyman series? Show Answer


Q152) 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 Show Answer


Q153) Which of the following lines of the H-atom spectrum belongs to the Balmer series? Show Answer


Q154) The production of band spectra is caused by Show Answer


Q155) Three photons coming from excited atomic hydrogen sample are observed, their energies are 12.1 eV, 10.2 eV and 1.9 eV. These photons must come from Show Answer


Q156) Electrons in the atom are held to the nucleus by Show Answer


Q157) The magnetic moment of the ground state of an atom whose open sub-shell is half-filled with five electrons is Show Answer


Q158) The energy of a hydrogen atom in its ground state is −13.6eV. The energy of the level corresponding to the quantum number n=5 is Show Answer


Q159) The spectral series of the hydrogen atom that lies in the visible ragion of the electromagnetic spectrum Show Answer


Q160) An electron collides with a hydrogen atom in its ground state and excites it to n=3. The energy given to hydrogen atom in this inelastic collision is(neglect the recoiling of hydrogen atom) Show Answer


Q161) The required energy to detach one electron from Balmer series of hydrogen spectrum is Show Answer


Q162) Which of the following transition gives the photon of minimum frequency? Show Answer


Q163) If series limit of Balmer series is 6400 Å, then series limit of Paschen series will be Show Answer


Q164) The binding energy of the electron in the lowest orbit of the hydrogen atom is 13.6 eV. The energies required in eV to remove an electron from the three lowest orbits of the hydrogen atom are Show Answer


Q165) Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be Show Answer


Q166) The nucleus of an atom consists of Show Answer


Q167) The ratio of minimum wavelengths of Lyman and Balmer series will be Show Answer


Q168) The ratio of the energies of the hydrogen atom in its first to second excited states is Show Answer


Q169) Two energy lavels of an electron in an atom are separated by 2.3 eV. The frequency of radiation emitted when the electrons go from higher to lower level is Show Answer


Q170)
When an electron jumps from the orbit n=2 to n=4,then wavelength of the radiations absorbed will be (R is Rydberg’s constant) Show Answer


Q171) The spectrum of an oil flame is an example for Show Answer


Q172) At the time of total solar eclipse, the spectrum of solar radiation will have Show Answer


Q173) The ground state energy of hydrogen atom is −13.6 eV. When its electron is in the first excited state, its excitation energy is Show Answer


Q174) Wavelength of light emitted from second orbit to first orbit in a hydrogen atom is Show Answer


Q175) If the wavelength of the first line of the balmer series of hydrogen is 6561Å, the wavelength of the second line of the series should be Show Answer


Q176) If an electron is revolving around the hydrogen nucleus at a distance of 0.1 nm, what would be its speed? Show Answer


Q177) The acceleration of electron in the first orbit of hydrogen atom is Show Answer


Q178) The ratio of longest wavelength and the shortest wavelength observed in the fifth spectral series of emission spectrum of hydrogen is Show Answer


Q179) Of the following transition in the hydrogen atom, the one which gives an emission line of the highest frequency is Show Answer


Q180) Which of the following radiations has the least wavelength Show Answer


Q181) Whenever a hydrogen atom emits a photon in the Balmer series Show Answer


Q182) The ratio of the energies of the hydrogen atom in its first to second excited state is Show Answer


Q183) Radio carbon dating is done by estimating in specimen the Show Answer


Q184) Which of the following is suitable for the fusion process Show Answer


Q185) The ratio between Bohr radii are Show Answer


Q186) During a nuclear fusion reaction Show Answer


Q187) The graph between number of decayed atoms N′ of a radioactive element and time t is Show Answer


Q188) Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4.
Then the number of spectral lines in the emission spectra will be
Show Answer


Q189) The ratio of the longest to shortest wavelengths in Bracket series of hydrogen spectra is Show Answer


Q190) The ratio of the frequencies of the long wavelength limits of Lyman and Balmer series of hydrogen spectrum is Show Answer


Q191) It is easier to ionize hydrogen as compared to deuterium, because Show Answer


Q192) Half-life of radio-active substance is 140 days. Initially, is 16 g. Calculate the time for this substance when it reduces to 1 g Show Answer


Q193) If scattering particles are 56 for 90° angle, then at an angle 60° it will be Show Answer


Q194) The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an Show Answer


Q195) What fraction of a radioactive material will get disintegrated in a period of two half-lives Show Answer


Q196) The number of revolutions per second made by an electron in the first Bohr orbit of hydrogen atom is of the order of Show Answer


Q197) As mass number increases ,surface area Show Answer


Q198) Mark the correct statement Show Answer


Q199) The S.I. unit of radioactivity is Show Answer


Q200) When a proton, anti-proton annihilate ,the energy released is Show Answer


Q201) What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jumps from fourth orbit to second orbit and from third orbit to second orbit Show Answer


Q202) According to classical theory, the circular path of an electron in Rutherford atom is Show Answer


Q203) A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is Show Answer


Q204) Nuclear forces are Show Answer


Q205) Number of spectral lines in hydrogen atom is Show Answer


Q206) In gamma ray emission from a nucleus Show Answer


Q207) Nuclear fusion is common to the pair Show Answer


Q208) The color of the second line of Balmer series is Show Answer


Q209) The nuclei of which of the following pairs of nuclei are isotones Show Answer


Q210) The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true Show Answer


Q211) 1 curie represents Show Answer


Q212) The mass number of a nucleus is equal to the number of Show Answer


Q213) Neutron is a particle, which is Show Answer


Q214) Which of the following is not conserved in nuclear reaction? Show Answer


Q215) In any Bohr orbit of the hydrogen atom, the ratio of kinetic energy to potential energy of the electron is Show Answer


Q216) The fact that photons carry energy was established by Show Answer


Q217) Carbon dating is best suited for determining the age of fossils of their age in years is of the order of Show Answer


Q218) The energy equivalent to 1 mg of matter in MeV is Show Answer


Q219) White light is passed through a dilute solution of potassium permanganate. The spectrum produced by the
emergent light is
Show Answer


Q220) Which of the following statements is true
Show Answer


Q221) Which of the following phenomena suggests the presence of electron energy levels in atoms Show Answer


Q222) Which one of the following nuclear reaction is a source of energy in the sun? Show Answer


Q223) The wavelength of the first line of Balmer series is 6563 Å. The Rydberg constant for hydrogen is about Show Answer


Q224) 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


Q225) The fussion process is possible at high temperatures, because at higher temperatures Show Answer


Q226) In a radioactive disintegration , the ratio of initial number of atoms to the number of atoms present at an instant of time equal to its mean life is Show Answer


Q227) Cadmium rods are used in a nuclear reactor for Show Answer


Q228) Which shows radioactivity? Show Answer


Q229) Which of these is a fusion reaction Show Answer


Q230) The energy required to excite an electron from the ground state of hydrogen atom to the first excited state, is Show Answer


Q231) The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the Show Answer


Q232) Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be Show Answer


Q233) Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become Show Answer


Q234) The half-life of radon is 3.8 days. How many radon will be left out of 1024 mg after 38 days Show Answer


Q235) Two nuclei have their mass numbers in the ratio of 1:3. The ratio of their nuclear densities would be Show Answer


Q236) Isobars are formed by Show Answer


Q237) The fraction of the initial number of radioactive nuclei which remain undecayed after half of a half-life of the radioactive sample is Show Answer


Q238) A radioactive substance has an average life of 5h. In a time of 5 h Show Answer


Q239) If the binding energy per nucleon of deutron is 1.115 MeV, its mass defect in atomic mass unit is Show Answer


Q240) Sun maintains its shining because of the Show Answer


Q241) The neutron was discovered by Show Answer


Q242) With the increase in principal quantum number, the energy difference between the two successive energy levels Show Answer


Q243) The ratio of ionization energy of Bohr’s hydrogen atom and Bohr’s hydrogen like lithium atom is Show Answer


Q244) The ratio of the longest to shortest wavelengths in Lyman series of hydrogen spectra is Show Answer


Q245) If the speed of light were 2/3 of its present value, the energy released in a given atomic explosion will be decreased by a fraction Show Answer


Q246) Fusion reaction take place at high temperature because Show Answer


Q247) Plutonium decays with half-life of 24000 yr. If plutonium is stored for 7200 yr, the fraction of it that remains is Show Answer


Q248) The atoms of same element having different masses but same chemical properties, are called Show Answer


Q249) A freshly prepared radioactive source of half-life 2 h emits radiation of intensity which is 64 times the permissible safe level. Calculate the minimum time after which it would be possible to work safely with this source. Show Answer


Q250) In Raman effect, Stoke’s lines are spectral lines having Show Answer


Q251) Which of the following is true Show Answer


Q252) Ratio of the wavelengths of first line of Lyman series and first time of Balmer series is Show Answer


Q253) In the lowest energy level of hydrogen atom, the electron has the angular momentum Show Answer


Q254) Which one of the following is a possible nuclear reaction? Show Answer


Q255) In a radioactive decay, neither the atomic number nor the mass number of changes. Which of the following would be emitted in the decay process Show Answer


Q256) The first line of Balmer series has wavelength 6563 Å. What will be the wavelength of the first member of Lyman series Show Answer


Q257) Which of the following is not conserved in nuclear reaction? Show Answer


Q258) The kinetic energy of an electron revolving around a nucleus will be Show Answer


Q259) 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 Show Answer


Q260) Ionization power and penetration range of radioactive radiation increases in the order Show Answer


Q261) The phenomena in which proton flips is Show Answer


Q262) One milligram of matter converted into energy will give Show Answer


Q263) Which one of the following nuclear reactions is a source of energy in the sun Show Answer


Q264) For nuclear forces to be effective, the distance should be Show Answer


Q265) If a proton and anti-proton come close to each other and annihilate, how much energy will be released Show Answer


Q266) Two lithium nuclei in a lithium vapour at room temperature do not combine to form a carbon nucleus because Show Answer


Q267) Atomic reactor is based on Show Answer


Q268) Pick out the correct statement from the following Show Answer


Q269) The change density in a nucleus varies with distance from the centre of the nucleus according to the curve in Fig. Show Answer


Q270) The ratio of the nuclear radii of elements with mass numbers 216 and 125 is Show Answer


Q271) A free neutron decays spontaneously into Show Answer


Q272) A radioactive sample at any instant has its disintegration rate 5000 disintegrations per minute. After 5 min, the rate becomes 1250 disintegration per minute. Then ,its decay constant (per minute) is Show Answer


Q273) The functions of moderators in nuclear reactor is to Show Answer


Q274) Which of the following transitions will have highest emission wavelength Show Answer


Q275) Hydrogen bomb is based on which of the following phenomenon Show Answer


Q276) When hydrogen atom is in its first excited level, its radius is …… its ground state radius Show Answer


Q277) What is the disintegration constant of radon if the number of its atoms diminishes by 18%in 24 h? Show Answer


Q278) Which of the relation is correct between time period and number of orbits while an electron is revolving in an orbit Show Answer


Q279) Boron rods in nuclear reactor are used as a Show Answer


Q280) Select the true statement from the following. Nuclear force is Show Answer


Q281) One Becquerel is defined as Show Answer


Q282) When the number of nucleons in nuclei increase, the binding energy per nucleon Show Answer


Q283) A chain reaction is continuous due to Show Answer


Q284) The ratio of longest wavelength and the shortest wavelength observed in the five spectral series of emission spectrum of hydrogen is Show Answer


Q285) The example of nuclear fusion is Show Answer


Q286) Age of a tree is determined using radio-isotope of Show Answer


Q287) The binding energy per nucleon for deuteron and helium are 1.1MeV and 7.0MeV. The energy released
when two deuterons fuse to form a helium nucleus is Show Answer


Q288) Half-life of a radio active substance A is 4 days. The probability that a nucleus will decay in two half-lives is Show Answer


Q289) In a sample of 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


Q290) In radioactive decay process, the negatively charged emitted β− particles are Show Answer


Q291) A radioactive material decays by simultaneous emission of two particles with half-lives 1620 yr and 810 yr respectively. The time in year after which one-fourth of the material remains , is Show Answer


Q292) What is used as a moderator in a nuclear reactor? Show Answer


Q293) Mean life of neutron is about Show Answer


Q294) To explain his theory, Bohr used Show Answer


Q295) A radioactive substance has a half-life of four months. Three-fourth of the substance will decay in Show Answer


Q296) According to Bohr’s theory, the moment of momentum of an electron revolving in second orbit of
hydrogen atom will be Show Answer


Q297) Which of the following pairs is an isobar Show Answer


Q298) 80 kg of a radioactive material reduces to 10 kg in 1 h. The decay constant of the material is Show Answer


Q299) The average binding energy per nucleon is maximum for the nucleus Show Answer


Q300) If half life of radium is 77 days. Its decay constant in day will be Show Answer


Q301) We have seen that a gamma-ray dose of 3Gy is lethal to half the people exposed to it. If the equivalent
energy were absorbed as heat, what rise in body temperature would result? Show Answer


Q302) Which one is correct about fission? Show Answer


Q303) In nuclear fission, the fission reactions proceeds with a projectile. Which of the following suits the best Show Answer


Q304) In a sample of hydrogen like atoms all of which are in ground state, a photon beam containing photons of
various energies is passed. In absorption spectrum, five dark lines, are observed. The number of bright
lines in the emission spectrum will be (assume that all transitions takes place) Show Answer


Q305) Heavy water is used as moderator in a nuclear reactor. The function of the moderator is Show Answer


Q306) A radioactive element forms its own isotope after 3 consecutive disintegrations. The particles emitted are Show Answer


Q307) Half life of radioactive element depends upon Show Answer


Q308) Consider the following statementsS1 : The nuclear force is independent of the charge of nucleons
S2 : The number of nucleons in the nucleus of an atom is equal to the number of electrons in the atom
S3 : All nuclei have masses that are less than the sum of the masses of constituent nucleons
S4 : Nucleons belong to the family of leptons while electrons are members of the family of hadrons
Choose the correct statement(s) from these Show Answer


Q309) The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species is Show Answer


Q310) If half-life of radium is 77days,its decay constant will be Show Answer


Q311) The ratio of molecular mass of two radioactive substances is 3/2 and the ratio of their decay constants is 4/3. Then, the ratio of their initial activity per mole will be Show Answer


Q312) In half life of a radio isotope is 2 seconds and number of atoms are only 4, then after one half life remaining (without decay) atoms are probably Show Answer


Q313) Which one of the following statements about uranium is correct Show Answer


Q314) If an electron and a positron annihilate, then the energy released is Show Answer


Q315) The density of uranium is of the order of Show Answer


Q316) Radioactive substances do not emit Show Answer


Q317) Neutrino emission in β−decay was predicted theoretically by Show Answer


Q318) Most suitable element for nuclear fission is the element with atomic number near Show Answer


Q319) After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000dps after another 140 days. The initial activity of the sample(in dps) is Show Answer


Q320) Nucleus of an atom whose atomic mass is 24 consists of Show Answer


Q321) The control rod in a nuclear reactor is made of Show Answer


Q322) A radioactive substance emits Show Answer


Q323) After two hours, one-sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half life of the isotope is Show Answer


Q324) An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be Show Answer


Q325) Alpha rays emitted from a radioactive substance are Show Answer


Q326) Which of the following statements are true regarding radioactivity (I) All radioactive elements decay exponentially with time (II) Half life time of a radioactive element is time required for one half of the radioactive atoms to disintegrate (III) Age of each can be determined with the help of radioactive dating (IV) Half life time of a radioactive element is 50% of its average life period Select correct answer using the codes given below Codes: Show Answer


Q327) The force acting between proton and proton inside the nucleus is Show Answer


Q328) In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life Show Answer


Q329) The de Broglie wave present in fifth Bohr orbit is Show Answer


Q330) A and B are two radioactive substances whose half-lives are 1 and 2 yr respectively. Initially 10 g of A and 1 g of B is taken. The time (approximate) after which they will have same quantity remaining is Show Answer


Q331) The ratio of the kinetic energy to the total energy of an electron in a Bohr orbit is Show Answer


Q332) Ionisation energy of an electron present in the second Bohr’s orbit of hydrogen is Show Answer


Q333) What percentage of original radioactive atoms is left after five half lives Show Answer


Q334) The mass number of a nucleus is 216. The size of an atom without changing its chemical properties are called Show Answer


Q335) A radioactive nucleus emits a beta particle. The parent and daughter nuclei are Show Answer


Q336) Hydrogen bomb is based upon Show Answer


Q337) Radius of the first orbit of the electron in a hydrogen atom is 0.53 Å. So, the radius of the third orbit will be Show Answer


Q338) Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called Show Answer


Q339) According to the Rutherford’s atomic model, the electrons inside the atom are Show Answer


Q340) A nucleus is bombarded with a high speed neutron so that resulting nucleus is a radioactive one. This phenomenon is called Show Answer


Q341) Sun energy is due to Show Answer


Q342) Mass of the nucleons together in a heavy nucleus is Show Answer


Q343) The mass of a neutron is the same as that of Show Answer


Q344) The spectral series of the hydrogen atom that lies in the visible region of the electromagnetic spectrum Show Answer


Q345) Size of nucleus is of the order of Show Answer


Q346) The ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is Show Answer


Q347) If a star can convert all the He nuclei completely into oxygen nuclei, the energy released per oxygen nuclei is ( Mass of the nucleus is 4.0026 amu and mass of oxygen nucleus is 15.9994 amu) Show Answer


Q348) The order of the size of nucleus and Bohr radius of an atom respectively are Show Answer


Q349) Who discovered spin quantum number Show Answer


Q350) For the stability of any nucleus Show Answer


Q351) The curve of binding energy per nucleon as a function of a atomic mass number has a sharp peak for helium nucleus. This implies that helium Show Answer


Q352) Radium has a half-life of 5 yr. The probability of decay of a radium nucleus in 10 yr is Show Answer


Q353) The ratio between total acceleration of the electron in singly ionized helium atom and hydrogen atom (both in ground state) is Show Answer


Q354) For maintaining sustained chain reaction, the following is required Show Answer


Q355) A radioactive material has a half life of 10 days. What fraction of the material would remain after 30 days Show Answer


Q356) The binding energy of an electron in the ground state of He is equal to 24.6 eV. The energy required to remove both the electrons is Show Answer


Q357) The splitting of line into groups under the effect of magnetic field is called Show Answer


Q358) Mean life of a radioactive sample is 100 s. Then its half-life(in minutes) is Show Answer


Q359) The half-life of a radioactive element is 3.8 days. The fraction left after 19 days will be Show Answer


Q360) The first member of the Paschen series in hydrogen spectrum is of wavelength 18,800 Å. The short wavelength limit of Paschen series is Show Answer


Q361) The wavelength of yellow line of sodium is 5896Å. Its wave number will be Show Answer


Q362) A radioactive sample at any instant has its disintegration rate 5000 disintegrations per minute. After 5 min, the rate is 1250 disintegrations per min. Then, the decay constant (per minute) is Show Answer


Q363) Nuclear fission experiments show that the neutrons split the uranium nuclei into two fragments of about same size. This process is accompanised by the emission of several Show Answer


Q364) If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately Show Answer


Q365) The ratio of areas within the electron orbits for the first excited state to the ground state for hydrogen
atom is Show Answer


Q366) Best neutron moderator is Show Answer


Q367) Half-life of radium is 1600 yr. Its average life is Show Answer


Q368) Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1eV. The spectral lines emitted by hydrogen atoms according to Bohr’s theory will be Show Answer


Q369) 3.8 days is the half-life period of a sample. After how many days, the sample will become 1/8th of the original substance Show Answer


Q370) When a hydrogen atom is raised from the ground state to an excited state Show Answer


Q371) Orbital acceleration of electron is Show Answer


Q372) An ionic atom equivalent to hydrogen atom has wavelength equal to 1/4 of the wavelength of hydrogen lines. The ion will be Show Answer


Q373) Which of the following particle has similar mass to electron Show Answer


Q374) Select the wrong statement Show Answer


Q375) The principle of controlled chain reaction is used in Show Answer


Q376) The radius of an electron orbit in a hydrogen atom is of the order of Show Answer


Q377) Which of the following is a fusion reaction? Show Answer


Q378) 1 atomic mass unit is equal to Show Answer


Q379) Thermal neutrons can cause fission in Show Answer


Q380) The subatomic particles proton and neutron fall under the group of Show Answer


Q381) The half -life period of a radioactive substance is 3 days. Three fourth of substance decays in Show Answer


Q382) According to the quark model, it is possible to build all the hadrons using Show Answer


Q383) The wavelength of Lyman series is Show Answer


Q384) Fusion reaction takes place at high temperature because Show Answer


Q385) Which of the following statements are true regarding Bohr’s model of hydrogen atom (I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus (II) Radii of allowed orbits of electron are proportional to the principal quantum number (III) Frequency with which electrons orbit around the nucleus is discrete orbits is inversely proportional to the cube of principal quantum number (IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits Select correct answer using the codes given below Show Answer


Q386) A radioactive substance of half-life 6 min is placed near a Geiger counter which is found to resister 1024 particles per minute. How many particles per minute will it register after 42 min? Show Answer


Q387) Nuclear fission was discovered by Show Answer


Q388) Li nucleus has three protons and four neutrons. Mass of lithium nucleus is 7.016005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect for lithium nucleus in amu is Show Answer


Q389) The average binding energy per nucleon in the nucleus of an atom is approximately Show Answer


Q390) The Bohr model of atom Show Answer


Q391) The de-Broglie wavelength of an electron in the first Bohr orbit is Show Answer


Q392) Half-life of radioactive sample, when activity of material initially was 8 counts and after 3 h it becomes 1 count, is Show Answer


Q393) The set which represents the isotope, isobar and isotone respectively is Show Answer


Q394) Nuclear fusion is common to the pair Show Answer


Q395) An electron is Show Answer


Q396) The energy released in the explosion of an atom bomb is mainly due to Show Answer


Q397) Heavy water is Show Answer


Q398) In a mean life of a radioactive sample
Show Answer


Q399) Nuclear binding energy is equivalent to
Show Answer


Q400) The kinetic energy of electron in the first Bohr orbit of the hydrogen atom is
Show Answer


Q401) If the wavelength of the first line of the Balmer series of hydrogen is 6561 Å, the wavelength of the second
line of the series should be Show Answer


Q402) The wavelength of light emitted from second orbit to first orbits in a hydrogen atom is Show Answer


Q403) 99% of a radioactive element will decay between Show Answer


Q404) The speed of daughter nuclei is Show Answer


Q405) After five half lives what will be the fraction of initial substance Show Answer


Q406) Antiparticle of electron is Show Answer


Q407) Heavy water is used in a nuclear reactor to Show Answer


Q408) What is the radius of iodine atom (at. no. 53, mass number 126) Show Answer


Q409) The large scale destruction, that would be caused due to the use of nuclear weapons is called Show Answer


Q410) The rate of disintegration of fixed quantity of a radioactive element can be increased by Show Answer


Q411) In the following transitions, which one has higher frequency Show Answer


Q412) Curie is a unit of Show Answer


Q413) What was the fissionable material used in bomb dropped at Nagasaki (Japan) in the year 1945 Show Answer


Q414) Which of the following atoms has the lowest ionization potential Show Answer


Q415) Two protons exert a nuclear force on each other, the distance between them is Show Answer


Q416) The most stable particle in Baryon group is Show Answer


Q417) Fission of nuclei is possible because the binding energy per nucleon in them Show Answer


Q418) The size of an atom is of the order of Show Answer


Q419) According to Bohr’s model, the radius of the second orbit of helium atom is
Show Answer


Q420) Bohr’s atom model assumes
Show Answer


Q421) Which of the following is in the increasing order for penetrating power Show Answer


Q422) Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova
explosion 5 billion years ago. The probability of decay during the next time is Show Answer


Q423) Which of the following transition in Balmer series for hydrogen atom will have longest wavelength Show Answer


Q424) A free neutron decays into a proton, an electron and Show Answer


Q425) In nuclear reactions, we have the conservation of Show Answer


Q426) Which of these is non-divisible Show Answer


Q427) Which one of the following statement is true, if half-life of a radioactive substance is 1 month? Show Answer


Q428) A radioactive substance has half-life of 60 min. During 3 h, the fraction of the substance that has to be decayed. will be Show Answer


Q429) Half-life is measured by Show Answer


Q430) The phenomenon of radioactivity is Show Answer


Q431) A moderator is used in nuclear reactors in order to Show Answer


Q432) If the binding energies of a deuteron and an alpha particle are 1.125MeV and 7.2MeV, respectively , then the more stable of the two is Show Answer


Q433) In a working nuclear reactor, cadmium rods (control rods) are used to Show Answer


Q434) The rad is the correct unit used to report the measurement of Show Answer


Q435) The masses of two radioactive substances are same and their half-lives are 1 yr and 2 yr respectively. The ratio of their activities after 4 yr will be Show Answer


Q436) For effective nuclear forces, the distance should be Show Answer


Q437) The energy equivalent of the atomic mass unit is Show Answer


Q438) The concept of stationary orbits was proposed by Show Answer


Q439) If the series limit of Lymen series for Hydrogen atom is equal to the series limit of Balmer series for a hydrogen like atom, then atomic number of this hydrogen like atom will be Show Answer


Q440) In helium nucleus, there are Show Answer


Q441) Light energy emitted by stars is due to Show Answer


Q442) A radioactive element A decay into stable element B, initially a fresh sample of A is available. In this sample
variation in number of nuclei of B with time is shown by Show Answer


Q443) The energy equivalent to a kilogram of matter is about Show Answer


Q444) A photon creates a pair of electron positron with equal kinetic energy. Let kinetic energy of each particle is
0.29 MeV. Then what should be energy of the photon? Show Answer


Q445) Which of the following cannot be emitted by radioactive substances during their decay? Show Answer


Q446) The nuclear reactor at Kaiga is a Show Answer


Q447) Which one of the series of hydrogen spectrum is in the visible region Show Answer


Q448) The radius of nucleus is Show Answer


Q449) Which of the following is most unstable Show Answer