# 1st PUC physics Series-8

#### PUC Science 1st Year Physics Series-8 quiz

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1st PUC Physics Series 8

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Q.71 Radioactive material A has a decay constant 8λ and material B has a decay constant λ. Initially, they have the same number of nuclei. After what time, the ratio of the number of nuclei of material B to that A will be 1/e?

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Q.72 The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is

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Q.73 If the radius of the 13Al27 nucleus is taken to be RAl then the radius of 53Te125 nucleus is nearly

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Q.74 A nucleus of uranium decays at rest into nuclei of thorium and helium. Then,

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Q.75

The binding energy per nucleon of 3Li7 and 2He4 nuclei are 5.60 meV and 7.06meV respectively.

In the nuclear reaction 3Li7 + 1H1 ➡️ 2He4 +2He4+Q, the value of energy Q released is

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Q.76 Calculate the mass defect(amu/atom) for a 37Cl atom for which the actual mass is 36.966 amu.

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Q.77 The mass defect for an isotope is 0.410 amu/atom. Calculate the value of binding energy.

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Q.78 Which isotope below has the highest binding energy?

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Q.79 Which of the following sentences is incorrect?

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Q.80

A nucleus has a mass number A, atomic number Z and a binding energy B. The mass of neutron and proton are mn and mp respectively and cis the speed of light.

Which of the following expressions correctly represents the mass of the nucleus?