[{"id":15639,"question":"To explain his theory Bohr used","choices":[{"text":"Conservation of linear momentum","value":"A"},{"text":"Conservation of angular momentum","value":"B"},{"text":"Conservation of quantum frequency","value":"C"},{"text":"Conservation of energy","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":15638,"question":"The nuclear model of atom was proposed by","choices":[{"text":"J.J Thomson","value":"A"},{"text":"E.Rutherford","value":"B"},{"text":"Neil Bohr","value":"C"},{"text":"Summerfield","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":15637,"question":"Who explained the origin of the Fraunhofer lines?","choices":[{"text":"Fraunhoffer","value":"A"},{"text":"Kirchhoff","value":"B"},{"text":"Fresnel","value":"C"},{"text":"Snell","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":15636,"question":"Band spectrum in produced by","choices":[{"text":"H","value":"A"},{"text":"He","value":"B"},{"text":"H<sub>2</sub>","value":"C"},{"text":"Na","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":15635,"question":"In which of the following states does the incandescent substance give continuous spectrum?","choices":[{"text":"Vapours in atomic state","value":"A"},{"text":"Vapours in molecular state","value":"B"},{"text":"Solid or fluid in bulk state","value":"C"},{"text":"Solid or fluid in plasma state","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":15634,"question":"Which of the following sources give discrete emission spectrum?","choices":[{"text":"Incandescent electric bulb","value":"A"},{"text":"Sun","value":"B"},{"text":"Mercury vapour lamp","value":"C"},{"text":"Candle","value":"D"},{"value":"E"}],"correctAnswer":3},{"id":15633,"question":"There are discrete energy levels in atoms. It was first experimentally demonstrated by","choices":[{"text":"Rutherford's experiment","value":"A"},{"text":"Frank Hertz experiment","value":"B"},{"text":"Marsden's experiment","value":"C"},{"text":"Sommerfield experiment","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":15632,"question":"The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to","choices":[{"text":"√V","value":"A"},{"text":"V<sup>2</sup>","value":"B"},{"text":"1/√V","value":"C"},{"text":"1/V","value":"D"},{"value":"E"}],"correctAnswer":4},{"id":15631,"question":"The essential distinction between X-rays and y-rays is that","choices":[{"text":"y-rays have smaller wavelength than X-rays","value":"A"},{"text":"y-rays emanate from nucleus while X-rays emanate from outer part of the atom","value":"B"},{"text":"y-rays have greater ionizing power than X-rays","value":"C"},{"text":"y-rays are more penetrating than X-rays","value":"D"},{"value":"E"}],"correctAnswer":2},{"id":15630,"question":"A photoelectric cell converts","choices":[{"text":"Electrical energy to light energy","value":"A"},{"text":"Light energy to light energy","value":"B"},{"text":"Light energy to electrical energy","value":"C"},{"text":"Light energy to elastic energy","value":"D"},{"value":"E"}],"correctAnswer":3}]