[{"id":254001,"question":"A thorium nucleus is formed when a uranium nucleus emits an π‘Ž βˆ’particles. Atomic\r\nnumber of thorium is :","choices":[{"text":"23","value":"A"},{"text":"60","value":"B"},{"text":"90","value":"C"},{"text":"70","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":254000,"question":"When an electron in an atom goes from a lower to higher its:","choices":[{"text":"K.E. increases, P.E. decreases","value":"A"},{"text":"K.E. increases","value":"B"},{"text":"P.E increases","value":"C"},{"text":"K.E. decrease, P.E. increases","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253999,"question":"When a radioactive nucleus emits a 𝖰 βˆ’paritcles, the mass number of the atom:","choices":[{"text":"Increases by one","value":"A"},{"text":"Decreases by one","value":"B"},{"text":"Remains the same","value":"C"},{"text":"Decreases by four","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253998,"question":"The shortest wavelength of X-rays emitted from an X-rays tube depends on the:","choices":[{"text":"Current in the tube","value":"A"},{"text":"Voltage applied to the tube","value":"B"},{"text":"Nature of gas in the tube","value":"C"},{"text":"Nature of material of tube","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253997,"question":"In an π‘Ž βˆ’decay:","choices":[{"text":"The parent and daughter nuclei have same number of protons","value":"A"},{"text":"The daughter nucleus has one proton more than parent nucleus","value":"B"},{"text":"The daughter nucleus has two protons less than parent nucleus","value":"C"},{"text":"The daughter nucleus has two neutrons more than parent nucleus","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253996,"question":"For X-rays which of the following is not correct:","choices":[{"text":"Cause of ionization in air when they pass through it","value":"A"},{"text":"Can be deflected by electric and magnetic fields","value":"B"},{"text":"Can be used to detect flaws in metal casting","value":"C"},{"text":"Travel with the speed of light","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253995,"question":"Half-life of radon gas is:","choices":[{"text":"1620 years","value":"A"},{"text":"3.8 days","value":"B"},{"text":"7 days","value":"C"},{"text":"11 days","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253994,"question":"
Ultraviolet radiation of 6.2 eV falls on an aluminium surface having work function βˆ… = πŸ’. 𝟐 𝒆𝑽.
The kinetic energy of the fastest electron emitted is:
","choices":[{"text":"4 eV","value":"A"},{"text":"2 eV","value":"B"},{"text":"2.2 eV","value":"C"},{"text":"1.2 eV","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253993,"question":"The threshold frequency depends on the nature on:","choices":[{"text":"Natural frequency","value":"A"},{"text":"Photosensitive anode","value":"B"},{"text":"Photosensitive cathode","value":"C"},{"text":"Photon","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253991,"question":"Nuclear fission experiments show that the neutrons the uranium nuclei into two fragment\r\nof about the same size. This process is accompanied by the emission of several:","choices":[{"text":"Protons and positrons","value":"A"},{"text":"𝛼 βˆ’partilces","value":"B"},{"text":"neutrons","value":"C"},{"text":"Protons and 𝛼 βˆ’partilces","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253990,"question":"The frequency and work function of an incident photon are n andπ‹πŸŽ. If f0 is the threshold frequency, then necessary condition for the emission of photo electron is:","choices":[{"text":"< 𝑓0","value":"A"},{"text":"𝑓 β‰₯ 𝑓0","value":"B"},{"text":"f = 𝑓0/2","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253988,"question":"The example of nuclear fusion is:","choices":[{"text":"Formation of barium and krypton from uranium","value":"A"},{"text":"Formation of plutonium -235 from uranium -235","value":"B"},{"text":"Formation of helium from hydrogen","value":"C"},{"text":"Formation of water from hydrogen and oxygen","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253987,"question":"The momentum of the moving photon is:","choices":[{"text":"Zero","value":"A"},{"text":"β„Ž","value":"B"},{"text":"πœ†","value":"C"},{"text":"β„Žπœ†","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253985,"question":"π‘Ž, 𝖰 𝒂𝒏𝒅 radiations come out of radioactive substance:","choices":[{"text":"Spontaneously","value":"A"},{"text":"When it is put in a reactor","value":"B"},{"text":"When it is heated","value":"C"},{"text":"Under pressure","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253983,"question":"A radioactive substance has a half-life of 4 months. Three-fourths of the substance will\r\ndecay in:","choices":[{"text":"5months ","value":"A"},{"text":"6months ","value":"B"},{"text":"8months ","value":"C"},{"text":"7months ","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253981,"question":"For atomic nucleus, the binding energy per nucleon with increase in mass\r\nnumber:","choices":[{"text":"Increases continuously","value":"A"},{"text":"Remains same","value":"B"},{"text":"Decrease continuously","value":"C"},{"text":"First increases and then decreases with increase in mass number","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253979,"question":"A count rate 240 per minute reduces to 30 counts per min in 1 hour. The half-life of\r\nsource is:","choices":[{"text":"20min","value":"A"},{"text":"60min","value":"B"},{"text":"80min","value":"C"},{"text":"90min","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253977,"question":"The phenomenon of radioactivity is associated with:","choices":[{"text":"Fission of nucleus","value":"A"},{"text":"Disintegration of neutrons","value":"B"},{"text":"Emission of spectral lines","value":"C"},{"text":"Spontaneous disintegration of the nuclei of atoms","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253975,"question":"The mother and daughter elements with the emission of 𝖰 βˆ’ π’“π’‚π’šπ’”, are called:","choices":[{"text":"Isotopes","value":"A"},{"text":"Isobars","value":"B"},{"text":"Isomers","value":"C"},{"text":"Isodiapheres","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253974,"question":"The activity of a radioactive sample is 1.6 curie and half-life is 2.5 days. Its activity after\r\n10 days will be:","choices":[{"text":"0.8 Curie","value":"A"},{"text":"0.1Curie","value":"B"},{"text":"0.4 Curie","value":"C"},{"text":"0.16 Curie","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253973,"question":"In 420 days, the activity of a sample of polonium (Po) fell to one-eight of its initial value.\r\nThe half-life of polonium is :","choices":[{"text":"140days","value":"A"},{"text":"45days","value":"B"},{"text":"87days","value":"C"},{"text":"90days","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253972,"question":"A radioactive isotope πŸπŸ‘πŸ– 𝑼 decays consecutively to πŸπŸ‘πŸ’ 𝑼 the particles emitted are:","choices":[{"text":"One 𝛼 and one 𝛽","value":"A"},{"text":"Two 𝛼 and one 𝛽","value":"B"},{"text":"e 𝛼 and two 𝛽","value":"C"},{"text":"Two 𝛼 and two 𝛽\r\n","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253971,"question":"An electron and a proton are accelerated through the same potential. If their masses are me and mp respectively, then the ratio of their de-Broglie wavelength is:","choices":[{"text":"1","value":"A"},{"text":"mp/me","value":"B"},{"text":"me/mp","value":"C"},{"text":"","img":"253971_638248540205804524-RA4.png","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253970,"question":"The uranium Nucleus πŸπŸ‘πŸ– 𝑼 undergoes successive decays, emitting respectively π‘Ž βˆ’ π’“π’‚π’š,𝖰 βˆ’\r\nπ’“π’‚π’š 𝒂𝒏𝒅 βˆ’ π’“π’‚π’šπ’”. What is the atomic number and atomic mass of the resulting nucleus:","choices":[{"text":"90, 238","value":"A"},{"text":"91, 234","value":"B"},{"text":"92, 236","value":"C"},{"text":"92, 238","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253969,"question":"A radioactive nucleus can emit:","choices":[{"text":"Electron","value":"A"},{"text":"𝛼 particles","value":"B"},{"text":"Positron","value":"C"},{"text":"Any of these","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253968,"question":"Which of the following have maximum ionization power?","choices":[{"text":"𝛼 βˆ’rays","value":"A"},{"text":"𝛽 βˆ’rays","value":"B"},{"text":"𝛾 βˆ’rays","value":"C"},{"text":"Same for all","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253967,"question":"Due to emission of 𝖰+ βˆ’ π’“π’‚π’šπ’”:","choices":[{"text":"Mass of the nucleus increases","value":"A"},{"text":"Mass of the nucleus decreases","value":"B"},{"text":"Charge on the nucleus increases","value":"C"},{"text":"Charge number decreases","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253961,"question":"Light elements do not emit X-rays because","choices":[{"text":"Electrons in it have high binding energy","value":"A"},{"text":"These materials are non- material","value":"B"},{"text":"There is a small difference in their energy shells","value":"C"},{"text":"Electrons in it require very large energy to remove from these materials","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":253960,"question":"Of electron of 50 keV strike a heavy target. Then radiation emitted by target will be","choices":[{"text":"Visible light","value":"A"},{"text":"Radio waves","value":"B"},{"text":"Ultraviolet","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253959,"question":"Continuous spectrum of X-rays id due to an effect known as","choices":[{"text":"Photoelectric effect","value":"A"},{"text":"Compton effect","value":"B"},{"text":"Heisenberg effect","value":"C"},{"text":"Bremsstrahlung","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253958,"question":"Which of the following statement is true about soft X-rays?","choices":[{"text":"They have large wavelength","value":"A"},{"text":"They have high energy","value":"B"},{"text":"They have low energy","value":"C"},{"text":"Both A and C","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253957,"question":"Light of frequency 1.5 times the threshold frequency is incident on a photo sensitive material. If the frequency is halved and intensity is doubled the photo electric current becomes","choices":[{"text":"Four times","value":"A"},{"text":"Half","value":"B"},{"text":"Double","value":"C"},{"text":"Zero","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":253956,"question":"The half-life of a radioactive element which has only 1//32 of its original mass left after a\r\nlapse of 60 days is:","choices":[{"text":"12days","value":"A"},{"text":"10days","value":"B"},{"text":"22days","value":"C"},{"text":"36days","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253955,"question":"The maximum energy of the electrons released in a photo cell is independent of:","choices":[{"text":"Frequency of incident light","value":"A"},{"text":"Intensity of incident light","value":"B"},{"text":"Nature of cathode rays","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253954,"question":"The minimum energy required to remove an electron is called:","choices":[{"text":"Stopping potential","value":"A"},{"text":"Work function","value":"B"},{"text":"Kinetic energy","value":"C"},{"text":"None of these","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253953,"question":"electrons from the surface of a metal when:","choices":[{"text":"It is heated to a high temperature","value":"A"},{"text":"Radiation of suitable wavelength falls on it","value":"B"},{"text":"Electrons of suitable velocity strike it","value":"C"},{"text":"It is placed in a strong electric field","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253952,"question":"The half-life of a certain element is 3.5 days at STP. If the temperature is doubled and\r\npressure is reduced to half then half-life of the same element will be:","choices":[{"text":"1.75 days","value":"A"},{"text":"3.5 days","value":"B"},{"text":"7 days","value":"C"},{"text":"14 days","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":253951,"question":"Which of the following is not true?","choices":[{"text":"The Lyman series is a continuous spectrum","value":"A"},{"text":"The Ballmer series is a line spectrum in the visible region","value":"B"},{"text":"The Paschen series is a line spectrum in the infrared region","value":"C"},{"text":"The spectral series formula can be derived from Rutherford’s model of the hydrogen atom 18. The photoelectric effect is the ejection of","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253950,"question":"If the radioactive substance reduces to 𝟏\r\nπŸπŸ”\r\nPHYSICS\r\nof its original mass in 40 days then its half-life\r\nis:","choices":[{"text":"10days","value":"A"},{"text":"20days","value":"B"},{"text":"40days","value":"C"},{"text":"4days","value":"D"},{"value":"E"}],"correctAnswer":1},{"id":253949,"question":"An electron in the n=1 orbit hydrogen atom is bound by 13.6 eV. If a hydrogen atom is in the n=3 state, how much energy is required to ionize it:","choices":[{"text":"13.6 eV","value":"A"},{"text":"4.53 eV","value":"B"},{"text":"3.4 eV","value":"C"},{"text":"1.51eV","value":"D"},{"value":"E"}],"correctAnswer":4}]