Practice Test


1) The total energy E of the electron in a hydrogen atom is


2) 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


3) The wavelength of the second spectral lines in the Lyman series of the hydrogen spectrum is


4) What is the shortest wavelength present in the Paschen series of the spectral lines ?


5) 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


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


7) The reaction that indicates beta-minus decay is


8) The reaction that indicates beta-plus decay is


9) One of the following is not used as a moderator in a nuclear reactor


10) A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to 3.125% ?


11) When a hydrogen atom is raised from the ground state to an excited state


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


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


14) In which of the following transitions will the wavelength be minimum ?


15) The series limit wavelength of the Lyman series for hydrogen atom is give by


16) 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


17) Which of the following is true ?


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


19) During a negative beta decay


20) Pick out the statement which is true


21) Fusion reaction takes place at high temperature because


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


23) 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.


24) What are number of nuclei of C, when number of nuclei of A and B are equal ?


25) At what time rate of disintegration of A and B are equal ?


26) Which of the following process represents a gamma-decay ?


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


28) 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)


29) In final state :


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


31) The mass number of a nucleus is


32) 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


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


34) 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


35) The Lyman series of hydrogen spectrum lies in the region


36) The size of an atom is of the order of


37) Which one of the series of hydrogen spectrum is in the visible region


38) Which of the following is true


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


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


41) The ionization potential for second He electron is


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


43) 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


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


45) 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


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


47) 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


48) The ionisation energy of 10 times ionised sodium atom is


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


50) Which of the following particles are constituents of the nucleus


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


52) The neutron was discovered by


53) The mass number of a nucleus is


54) The energy equivalent of 1 kilogram of matter is about


55) Nuclear binding energy is equivalent to


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


57) Which of the following has the mass closest in value to that of the positron


58) Size of nucleus is of the order of


59) For effective nuclear forces, the distance should be


60) 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)


61) 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


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


63) One microgram of matter converted into energy will give


64) The average binding energy per nucleon in the nucleus of an atom is approximately


65) Binding energy of a nucleus is


66) Which of the following pairs is an isobar


67) Equivalent energy of mass equal to 1 a.m.u. is


68) The mass number of a nucleus is equal to the number of


69) The rest energy of an electron is


70) Outside a nucleus


71) Nucleus of an atom whose atomic mass is 24 consists of


72) The mass of a neutron is the same as that of


73) The mass defect per nucleon is called


74) The element used for radioactive carbon dating for more than 56000 yr is


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


76) Which is the correct expression for half-life


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


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


79) The ratio of minimum wavelength of Lyman and Balmer series will be


80) 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?


81) 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


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


83) In Raman effect, Stokes’ lines are spectral lines having


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


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


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


87) 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?


88) 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


89) 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?


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


91) The angular momentum of electron in hydrogen atom is proportional to


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


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


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


95) The atomic number and the mass number of an atom remains unchanged when it emits


96) The Rydberg constant R for hydrogen is


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


98) 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


99) The ratio of the frequencies of the long wavelength limits of the Lyman and Balmer series of hydrogen is


100) 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


101) The ratio of minimum to maximum wavelength in Balmer series is


102) Solar spectrum is an example for


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


104) 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


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


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


107) Mercury vapour lamp gives


108) 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


109) 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


110) 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


111) A neon sign does not produce


112) If a is radius of first Bohr orbit in hydrogen atom, the radius of the third orbit is


113) In the Bohr’s model of the hydrogen atom, the lowest orbit corresponds to


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


115) The colour of the second line of Balmer series is


116) Continuous emission spectrum is produced by


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


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


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


120) 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


121) The shortest wavelength in Lyman series is 91.2 nm. The longest wavelength of the series is


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


123) 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?


124) The series limit wavelength of the Lyman series for the hydrogen atom is given by


125) 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


126) 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


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


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


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


130) The ionisation energy of 10 time ionised sodium atom is


131) The spin-orbit interaction has no effect in the level of the hydrogen atom


132) Pick out the unmatched pair from the following


133) 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


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


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


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


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


138) 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


139) 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


140) 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


141) The orbital frequency of an electron in the hydrogen atom is proportional to


142) Which of the following isotopes is normally fissionable


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


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


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


146) The volume of a nucleus is directly proportional to


147) Solar energy is mainly cause due to


148) The ratio of minimum to maximum wavelength in Balmar series is


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


150) In beta decay


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


152) 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


153) Which of the following lines of the H-atom spectrum belongs to the Balmer series?


154) The production of band spectra is caused by


155) 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


156) Electrons in the atom are held to the nucleus by


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


158) 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


159) The spectral series of the hydrogen atom that lies in the visible ragion of the electromagnetic spectrum


160) 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)


161) The required energy to detach one electron from Balmer series of hydrogen spectrum is


162) Which of the following transition gives the photon of minimum frequency?


163) If series limit of Balmer series is 6400 Å, then series limit of Paschen series will be


164) 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


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


166) The nucleus of an atom consists of


167) The ratio of minimum wavelengths of Lyman and Balmer series will be


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


169) 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


170)
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)


171) The spectrum of an oil flame is an example for


172) At the time of total solar eclipse, the spectrum of solar radiation will have


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


174) Wavelength of light emitted from second orbit to first orbit in a hydrogen atom is


175) 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


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


177) The acceleration of electron in the first orbit of hydrogen atom is


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


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


180) Which of the following radiations has the least wavelength


181) Whenever a hydrogen atom emits a photon in the Balmer series


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


183) Radio carbon dating is done by estimating in specimen the


184) Which of the following is suitable for the fusion process


185) The ratio between Bohr radii are


186) During a nuclear fusion reaction


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


188) 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


189) The ratio of the longest to shortest wavelengths in Bracket series of hydrogen spectra is


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


191) It is easier to ionize hydrogen as compared to deuterium, because


192) 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


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


194) 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


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


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


197) As mass number increases ,surface area


198) Mark the correct statement


199) The S.I. unit of radioactivity is


200) When a proton, anti-proton annihilate ,the energy released is


201) 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


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


203) 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


204) Nuclear forces are


205) Number of spectral lines in hydrogen atom is


206) In gamma ray emission from a nucleus


207) Nuclear fusion is common to the pair


208) The color of the second line of Balmer series is


209) The nuclei of which of the following pairs of nuclei are isotones


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


211) 1 curie represents


212) The mass number of a nucleus is equal to the number of


213) Neutron is a particle, which is


214) Which of the following is not conserved in nuclear reaction?


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


216) The fact that photons carry energy was established by


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


218) The energy equivalent to 1 mg of matter in MeV is


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


220) Which of the following statements is true


221) Which of the following phenomena suggests the presence of electron energy levels in atoms


222) Which one of the following nuclear reaction is a source of energy in the sun?


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


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


225) The fussion process is possible at high temperatures, because at higher temperatures


226) 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


227) Cadmium rods are used in a nuclear reactor for


228) Which shows radioactivity?


229) Which of these is a fusion reaction


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


231) The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the


232) 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


233) 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


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


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


236) Isobars are formed by


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


238) A radioactive substance has an average life of 5h. In a time of 5 h


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


240) Sun maintains its shining because of the


241) The neutron was discovered by


242) With the increase in principal quantum number, the energy difference between the two successive energy levels


243) The ratio of ionization energy of Bohr’s hydrogen atom and Bohr’s hydrogen like lithium atom is


244) The ratio of the longest to shortest wavelengths in Lyman series of hydrogen spectra is


245) 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


246) Fusion reaction take place at high temperature because


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


248) The atoms of same element having different masses but same chemical properties, are called


249) 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.


250) In Raman effect, Stoke’s lines are spectral lines having


251) Which of the following is true


252) Ratio of the wavelengths of first line of Lyman series and first time of Balmer series is


253) In the lowest energy level of hydrogen atom, the electron has the angular momentum


254) Which one of the following is a possible nuclear reaction?


255) 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


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


257) Which of the following is not conserved in nuclear reaction?


258) The kinetic energy of an electron revolving around a nucleus will be


259) 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


260) Ionization power and penetration range of radioactive radiation increases in the order


261) The phenomena in which proton flips is


262) One milligram of matter converted into energy will give


263) Which one of the following nuclear reactions is a source of energy in the sun


264) For nuclear forces to be effective, the distance should be


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


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


267) Atomic reactor is based on


268) Pick out the correct statement from the following


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


270) The ratio of the nuclear radii of elements with mass numbers 216 and 125 is


271) A free neutron decays spontaneously into


272) 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


273) The functions of moderators in nuclear reactor is to


274) Which of the following transitions will have highest emission wavelength


275) Hydrogen bomb is based on which of the following phenomenon


276) When hydrogen atom is in its first excited level, its radius is …… its ground state radius


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


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


279) Boron rods in nuclear reactor are used as a


280) Select the true statement from the following. Nuclear force is


281) One Becquerel is defined as


282) When the number of nucleons in nuclei increase, the binding energy per nucleon


283) A chain reaction is continuous due to


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


285) The example of nuclear fusion is


286) Age of a tree is determined using radio-isotope of


287) 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


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


289) 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


290) In radioactive decay process, the negatively charged emitted β− particles are


291) 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


292) What is used as a moderator in a nuclear reactor?


293) Mean life of neutron is about


294) To explain his theory, Bohr used


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


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


297) Which of the following pairs is an isobar


298) 80 kg of a radioactive material reduces to 10 kg in 1 h. The decay constant of the material is


299) The average binding energy per nucleon is maximum for the nucleus


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


301) 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?


302) Which one is correct about fission?


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


304) 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)


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


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


307) Half life of radioactive element depends upon


308) 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


309) 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


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


311) 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


312) 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


313) Which one of the following statements about uranium is correct


314) If an electron and a positron annihilate, then the energy released is


315) The density of uranium is of the order of


316) Radioactive substances do not emit


317) Neutrino emission in β−decay was predicted theoretically by


318) Most suitable element for nuclear fission is the element with atomic number near


319) 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


320) Nucleus of an atom whose atomic mass is 24 consists of


321) The control rod in a nuclear reactor is made of


322) A radioactive substance emits


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


324) 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


325) Alpha rays emitted from a radioactive substance are


326) 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:


327) The force acting between proton and proton inside the nucleus is


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


329) The de Broglie wave present in fifth Bohr orbit is


330) 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


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


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


333) What percentage of original radioactive atoms is left after five half lives


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


335) A radioactive nucleus emits a beta particle. The parent and daughter nuclei are


336) Hydrogen bomb is based upon


337) 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


338) 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


339) According to the Rutherford’s atomic model, the electrons inside the atom are


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


341) Sun energy is due to


342) Mass of the nucleons together in a heavy nucleus is


343) The mass of a neutron is the same as that of


344) The spectral series of the hydrogen atom that lies in the visible region of the electromagnetic spectrum


345) Size of nucleus is of the order of


346) The ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is


347) 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)


348) The order of the size of nucleus and Bohr radius of an atom respectively are


349) Who discovered spin quantum number


350) For the stability of any nucleus


351) 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


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


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


354) For maintaining sustained chain reaction, the following is required


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


356) 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


357) The splitting of line into groups under the effect of magnetic field is called


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


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


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


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


362) 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


363) 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


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


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


366) Best neutron moderator is


367) Half-life of radium is 1600 yr. Its average life is


368) 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


369) 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


370) When a hydrogen atom is raised from the ground state to an excited state


371) Orbital acceleration of electron is


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


373) Which of the following particle has similar mass to electron


374) Select the wrong statement


375) The principle of controlled chain reaction is used in


376) The radius of an electron orbit in a hydrogen atom is of the order of


377) Which of the following is a fusion reaction?


378) 1 atomic mass unit is equal to


379) Thermal neutrons can cause fission in


380) The subatomic particles proton and neutron fall under the group of


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


382) According to the quark model, it is possible to build all the hadrons using


383) The wavelength of Lyman series is


384) Fusion reaction takes place at high temperature because


385) 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


386) 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?


387) Nuclear fission was discovered by


388) 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


389) The average binding energy per nucleon in the nucleus of an atom is approximately


390) The Bohr model of atom


391) The de-Broglie wavelength of an electron in the first Bohr orbit is


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


393) The set which represents the isotope, isobar and isotone respectively is


394) Nuclear fusion is common to the pair


395) An electron is


396) The energy released in the explosion of an atom bomb is mainly due to


397) Heavy water is


398) In a mean life of a radioactive sample


399) Nuclear binding energy is equivalent to


400) The kinetic energy of electron in the first Bohr orbit of the hydrogen atom is


401) 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


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


403) 99% of a radioactive element will decay between


404) The speed of daughter nuclei is


405) After five half lives what will be the fraction of initial substance


406) Antiparticle of electron is


407) Heavy water is used in a nuclear reactor to


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


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


410) The rate of disintegration of fixed quantity of a radioactive element can be increased by


411) In the following transitions, which one has higher frequency


412) Curie is a unit of


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


414) Which of the following atoms has the lowest ionization potential


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


416) The most stable particle in Baryon group is


417) Fission of nuclei is possible because the binding energy per nucleon in them


418) The size of an atom is of the order of


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


420) Bohr’s atom model assumes


421) Which of the following is in the increasing order for penetrating power


422) 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


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


424) A free neutron decays into a proton, an electron and


425) In nuclear reactions, we have the conservation of


426) Which of these is non-divisible


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


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


429) Half-life is measured by


430) The phenomenon of radioactivity is


431) A moderator is used in nuclear reactors in order to


432) 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


433) In a working nuclear reactor, cadmium rods (control rods) are used to


434) The rad is the correct unit used to report the measurement of


435) 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


436) For effective nuclear forces, the distance should be


437) The energy equivalent of the atomic mass unit is


438) The concept of stationary orbits was proposed by


439) 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


440) In helium nucleus, there are


441) Light energy emitted by stars is due to


442) 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


443) The energy equivalent to a kilogram of matter is about


444) 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?


445) Which of the following cannot be emitted by radioactive substances during their decay?


446) The nuclear reactor at Kaiga is a


447) Which one of the series of hydrogen spectrum is in the visible region


448) The radius of nucleus is


449) Which of the following is most unstable