A sample of radioactive elements contains $4×{10}^{10}$ active nuclei. If half-life of element is 10 days, then the number of decayed nuclei after 30 days is 

(1) $0.5×{10}^{10}$                   (2) $2×{10}^{10}$

(3) $3.5×{10}^{10}$                   (4) $1×{10}^{10}$

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A and B are two radioactive substances whose half-lives are 1 and 2 years respectively. Initially 10 g of A and 1 g of B is taken. The time (approximate) after which they will have the same quantity remaining is

(1) 6.62 yr                (2) 5 yr                (3) 3.2 yr                   (4) 7 yr

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In radioactive decay process, the negatively charged emitted $\beta$-particles are

(a) the electrons present inside the nucleus

(b) the electrons produced as a result of the decay of neutrons inside the nucleus

(c) the electrons produced as a result of collisions between atoms

(d) the electrons orbiting around the nucleus

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A sample of radioactive element has a mass of 10 gm at an instant t = 0. The approximate mass of this element in the sample after two means lives in [CBSE PMT/PDT 2003]

(1) 3.70 gm             (2) 6.30 gm             (3) 1.35 gm           (4) 2.50 gm

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Given a sample of Radium-226 having half-life of 4 days. Find the probability, a nucleus disintegrates after 2 half lives [IIT-JEE 2006]

(1) 1              (2) 1/2            (3) 1.5             (4) 3/4

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Complete the equation for the following fission process-

${U}_{92}^{235}+{n}_{0}^{1}\to S{r}_{38}^{90}+........$

(1)                       (2) $X{{e}_{{}_{54}}^{145}}^{}$

(3) $X{{e}_{{}_{57}}^{142}}^{}$                                   (4) $X{{e}_{{}_{54}}^{142}}^{}+{n}_{0}^{1}$

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Nuclear binding energy
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A nucleus ruptures into two nuclear parts, which have their velocity ratio equal to 2:1. what will be the ratio of their nuclear size (nuclear radius) ? 

(1)               (2)              (3)                 (4)

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Nuclear binding energy
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The half-life of a radioactive material is 3h. If the initial amount is 300g, then after 18h, it will remain

(a) 4.68 g                                     (b) 46.8 g

(c) 9.375 g                                   (d) 93.75 g

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Half-life of a radioactive substance is 20 min. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximately-

(1) 10 min            (2) 20 min            (3) 30 min            (4) 40  min

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When two deuterium nuclei fuse together to form a tritium nuclei, we get a [CPMT 2000]

(1) Neutron          (2) Deutron               (3) $\alpha$-particle               (4) Proton

Concept Questions :-

Nuclear binding energy