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23%20-%20Atoms,%20Molecules%20and%20Nuclei

23%20-%20Atoms,%20Molecules%20and%20Nuclei - 23 ATOMS...

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23 - ATOMS, MOLECULES AND NUCLEI Page 1 ( Answers at the end of all questions ) 1 ) If the radius of the 13 Al 27 nucleus is estimated to be 3.6 fermi, then the radius of 52 Te 125 nucleus will be nearly ( a ) 8 fermi ( b ) 6 fermi ( c ) 5 fermi ( d ) 4 fermi [ AIEEE 2005 ] 2 ) Starting with a sample of pure Cu 66 , 7 / 8th of it decays into Zn in 15 minutes. The corresponding half-life is ( a ) 15 minutes ( b ) 10 minutes ( c ) 7.5 minutes ( d ) 5 minutes [ AIEEE 2005 ] 3 ) The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy [ AIEEE 2005 ] 4 ) A nuclear transformation is denoted by X ( n, α ) 3 Li 7 . Which of the following is the nucleus of element X ? 5 ) If the kinetic energy of a free electron doubles, its de - Broglie wavelength changes by the factor 6 ) A nucleus disintegrates into two nuclear parts which have their velocities in the ratio 2 : 1. The ratio of their nuclear sizes will be ( a ) 1 : 2 3 1 ( b ) 2 1 3 : 1 ( c ) 1 : 3 2 1 ( d ) 3 1 2 : 1 [ AIEEE 2004 ] 7 ) The binding energy per nucleon of deuteron ( 1 H 2 ) and helium nucleus ( 2 He 4 ) is 1.1 MeV and 7 MeV respectively. If two deuteron nuclei reacts to form a single helium nucleus, then the energy released is 8 ) An α - particle of energy 5 MeV is scattered through 180 ° by a fixed uranium nucleus. The distance of the closest approach is of the order of 9 ) When U 238 nucleus originally at rest, decays by emitting an alpha particle having speed ‘u’, the recoil speed of the residual nucleus is 4u - 4u 4u - 4u [ AIEEE 2003 ] 10 ) A nucleus with Z = 92 emits the following in a sequence α, α, α, α, α, β - , β - , α, β + , α . The Z of the resulting nucleus is ( a ) 74 ( b ) 76 ( c ) 78 ( d ) 82 [ AIEEE 2003 ]
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23 - ATOMS, MOLECULES AND NUCLEI Page 2 ( Answers at the end of all questions ) 11 ) If the radioactive decay constant of radium is 1.07 × 10 - 4 per year, then the half-life period is approximately equal to 12 ) Which of the following cannot be emitted by radioactive substances during their decay ? [ AIEEE 2003 ] 13 ) Which of the following atoms has the lowest ionization potential ?
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