The half life (T) and the disintegration constant λ of a radioactive substance are related as
(a) λT=1                     (b) λT=0.693
(c) Tλ=0.693              (d) λT=0.693

Concept Questions :-

Radioactivity
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The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be

(a) 93.75%                  (b) 75%
(c) 25%                       (d) 6.25%

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Radioactivity
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In the uranium radioactive series, the initial nucleus is U92238 and the final nucleus is Pb82206. When the uranium nucleus decays to lead, the number of  α-particles emitted will be 
(a) 1                (b) 2
(c) 4                (d) 8

Concept Questions :-

Types of decay
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Which of the following is a correct statement

(a) Beta rays are same as cathode rays
(b) Gamma rays are high energy neutrons
(c) Alpha particles are singly ionized helium atoms
(d) Protons and neutrons have exactly the same mass

Concept Questions :-

Types of decay
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Ne22 nucleus after absorbing energy decays into two α-particles and an unknown nucleus. The unknown nucleus is 
(a) Nitrogen              (b) Carbon
(c) Boron                  (d) Oxygen

Concept Questions :-

Types of decay
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The half life of I131 is 8 days. Given a sample of I131 at time t = 0, we can assert that 
(a) No nucleus will decay before t = 4 days
(b) No nucleus will decay before t = 8 days
(c) All nuclei will decay before t = 16 days
(d) A given nucleus may decay at any time after t = 0

Concept Questions :-

Radioactivity
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Carbon-14 decays with half-life of about 5,800 years. In a sample of bone, the ratio of carbon-14 to carbon-12 is found to be 14 of what it is in free air. This bone may belong to a period about x centuries ago, where x is nearest to 
(a) 2×58                        (b) 58
(c) 58/2                          (d) 3×58

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Radioactivity
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In the disintegration series U92238αXβ-YZA
the values of Z and A respectively will be 
(a) 92, 236                (b) 88, 230
(c) 90, 234                (d) 91, 234

Concept Questions :-

Radioactivity
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The particles emitted by radioactive decay are deflected by magnetic field. The particles will be
(a) Protons and α-particles
(b) Electrons, protons and α-particles
(c) Electrons, protons and neutrons
(d) Electrons and α-particles

Concept Questions :-

Types of decay
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Half life of a radioactive element is 10 days. The time during which quantity remains 1/10 of initial mass will be
(a) 100 days             (b) 50 days
(c) 33 days               (d) 16 days

Concept Questions :-

Radioactivity
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