If in a nuclear fusion  process, the masses of the fusion nuclei be m1 and m2 and the mass of the resultant nucleus be m3, then [2004]

(1) m3=m1+m2                     (2) m3=m1-m2

(3) m3<m1+m2                  (4) m3>m1+m2

Concept Questions :-

Mass-energy equivalent
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The nuclei of which one of the following pairs of nuclei are isotones? [2005]

(1) S34e74, G31a71                  (2) M42o92, Z40r92

(3) S38r84, S38r86                    (4) C20a40, S3216

Concept Questions :-

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The counting rate observed from a radio active source at t = 0 second was 1600 counts per second and at t = 8 seconds it was 100 counts per second. The counting rate observed, as counts per second, at t = 6 seconds will be

(1) 400         (2) 300         (3) 200        (4) 150

Concept Questions :-

Radioactivity
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If N0 is the original mass of the substance of half life period T1/2= 5 years, then the amount of substance left after 15 years is [AIEEE 2012]

(1) N0/8           (2) N0/16           (3) N0/2            (4) N0/4

Concept Questions :-

Radioactivity
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The numbers of nuclei of a radioactive substance at time t = 0 are 1000 and 900 at time t = 2 s. Then number of nuclei at time t = 4 s will be

(1) 800            (2) 810             (3) 790             (4) 700

Concept Questions :-

Radioactivity
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A nucleus XZA has mass represented by m(A, Z). If mp and mn denote the mass of proton and neutron respectively and BE the binding energy (in MeV), then [2007]

(1) BE = [m(A, Z) - Zmp- (A - Z)mnc2

(2) BE = [Zmp+ (A - Z)mn- m(A,Z)] c2

(3) BE = [Zmp+ Amn- m(A, Z)] c2

(4) BE = m(A, Z) - Zmp- (A, Z)mn

Concept Questions :-

Nuclear binding energy
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The equation XAZYAZ+1 + e0-1+ν¯ is          (UP CPMT 2002)

(1) β-emission                (2) α-emission

(3) e- capture                (4) fission

Concept Questions :-

Types of decay
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Half-lives of two radioactive substances A and B respectively 20 min and 40 min.  Initially, the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is [1998]

(1) 1 : 16                         (2) 4 : 1

(3) 1 : 4                           (4) 1 : 1

Concept Questions :-

Radioactivity
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Radioactive C2760o is transformed into stable N2860i by emitting two γ-rays of energies [Kerala PET 2010]

(1) 1.33 MeV and 1.17 MeV in succession

(2) 1.17 MeV and 1.33 MeV in succession

(3) 1.37 MeV and 1.13 MeV in succession

(4) 1.17 MeV and 1.13 MeV in succession

Concept Questions :-

Radioactivity
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The volume occupied by an atom is greater than the volume of the nucleus by factor of about [2003]

(1) 1010                (2) 1015                (3) 101                (4) 105

Concept Questions :-

Mass-energy equivalent
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