The eneray equ\'valent of mass defct of -0.1620 amu is which of the following? A

Question

The eneray equ'valent of mass defct of -0.1620 amu is which of the following? A)1.458 x 1016J B) -2.42 1x10-J C)-2.421 x 10 J D)-2.421 x I0 J E)-1.458 x 101J 40. If 24% of a certain radioisotope decays in 6.5 years, what is the half-life of this isotope? A) 3.9 yr/ B) 16 yr C) 0.22 yr E) 3.2 yr 41. Which one of the following statements about fission and fusion is false? Fission occurs among the heaviest isotopes, whereas fusion occurs more readily for light isotopes. A) B) For a fission reaction the mass defect (Am) is negative, whereas for fusion Am is C) positive In order for fusion reactions to occur, temperatures must be in the millions of degrees. The fission of Pu-239 atoms produces a great number of isotopes of a large number of elements. Neutron-induced fission processes can occur at room temperature, rather than at millions of degrees. D) E) 42. Which type of nuclear process requires an extremely high temperature (millions of degrees)? A) beta decay B) fission reaction C) fusion reaction D) alpha decay E) positron emission 43. In the following reaction, identify X. A) L c) "cr

Explanation / Answer

(39) Given the binding energy , m = 0.1620 amu

                                                 = 0.1620 x 1.67377 x 10 -27 kg      since 1 amu = 1.67377 x 10 -27 kg

                                                 = 2.71x10-28 kg

Energy E = mc2

C = speed of light = 2.997x108 m/s

Plug the values we get E = 2.71x10-28 kg x (2.997x108 m/s)2

                                    = 2.421x10-11 J

So option (C) is correct

(40) All the radioactive reactions are of first order reactions

For a first order reaction rate constant , k = ( 2.303 /t )x log ( Mo / M)

Where

Mo = initial mass = 100

M= Mass left after time t = 24

t = time = 6.5 years

Plug the values we get k = ( 2.303 /6.5 )x log (100/24)

                                    = 0.219 year-1

So half life , t1/2 = 0.693/k

                         = 0.693 / 0.219

                        = 3.2 years

So option (E) is correct

(41) The false statement is (B)

(42) For fusion reaction we require high temperature

So option (C) is correct

(43) In balancing the nuclear reactions the sum of the atomic numbers of the reactants is equal to the sum of the atomic number of the products , simillarly the sum of the atomic masses of the reactants is equal to the sum of the atomic masses of the products

98Cf252 +5B10 ------->103Lr 257 +5 0n1

So option (A) is correct

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