A nucleus AZA emits an α-particle. The resultant nucleus emits a β+ particle. The respective atomic and mass no. of the final nucleus will be 

1. Z – 3, A – 4           

2. Z – 1, A – 4

3. Z – 2, A – 4           

4. Z, A – 2

Subtopic:  Types of Decay |
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The activity of a radioactive sample is 1.6 curie and its half-life is 2.5 days. Its activity after 10 days will be

(1) 0.8 curie       

(2) 0.4 curie

(3) 0.1 curie       

(4) 0.16 curie

Subtopic:  Radioactivity (OLD NCERT) |
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In a mean life of a radioactive sample 

(1) About 1/3 of substance disintegrates

(2) About 2/3 of the substance disintegrates

(3) About 90% of the substance disintegrates

(4) Almost all the substance disintegrates

Subtopic:  Radioactivity (OLD NCERT) |
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Three fourth of the active decays in a radioactive sample in 3/4 sec. The half life of the sample is 
(1) 12 sec           

(2) 1 sec
(3) 38 sec           

(4) 34 sec

Subtopic:  Radioactivity (OLD NCERT) |
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During mean life of a radioactive element, the fraction that disintegrates is:

(1) e           

(2)  1e
(3) e-1e     

(4) ee-1

Subtopic:  Radioactivity (OLD NCERT) |
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1 Curie is equal to 

(1) 3×1010 disintegrations/sec

(2) 3.7×107 disintegrations/sec

(3) 5×107 disintegrations/sec

(4) 3.7×1010 disintegrations/sec

Subtopic:  Radioactivity (OLD NCERT) |
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The electron emitted in beta radiation originates from

(1) Inner orbits of atoms

(2) Free electrons existing in nuclei

(3) Decay of a neutron in a nucleus

(4) Photon escaping from the nucleus

Subtopic:  Types of Decay |
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When a radioactive substance emits an α-particle, its position in the periodic table is lowered by

(1) One place             

(2) Two places

(3) Three places           

(4) Four places

Subtopic:  Types of Decay |
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A radioactive nucleus emits a beta particle. The parent and daughter nuclei are 

(1) Isotopes             

(2) Isotones

(3) Isomers               

(4) Isobars

Subtopic:  Types of Decay |
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If a radioactive substance reduces to 116 of its original mass in 40 days, what is its half-life 

(1) 10 days           

(2) 20 days

(3) 40 days           

(4) None of these

Subtopic:  Radioactivity (OLD NCERT) |
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