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1) The reaction shown below is responsible for creating 14 C in the atmosphere.

ID: 866767 • Letter: 1

Question

1) The reaction shown below is responsible for creating 14C in the atmosphere. What is the bombarding particle? Reaction: 14N + ________ = 14C + 1H

proton

alpha particle

neutron

electron

positron

2) The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the mass defect (in amu) of a 60Co nucleus that has an exact mass of 59.9338 amu.

0.0662 amu

0.5405 amu

27.7830 amu

0.4827 amu

0.5489 amu

3) Uranium-235 fissions into a variety of products depending on how a particular atom splits apart. Suppose a neutron collides with an atom of U-235. The reaction creates a iodine-129 atom, two neutrons, and an atom with an atomic number of ______________.

Thank you

Explanation / Answer

1) 14N7 + 1n -------------> 14C6 + 1H1

See , total mass number on the L.H.S = total mass number of R.H.S = 15

Total electrons on L.H.S = Total electrons on R.H.S = 7

2) 60Co27 contains 27 electrons, 27 protons & 33 neutrons

Thus, mass of 60Co = 27*mass of 1 proton + 33*mass of 1 neutron = 60.48267 amu

Thus, mass defect = theoretical mass - actual mass = 60.48267 - 59.9338 = 0.54887 amu

Thus, the correct option is : 0.5489 amu

3) 235U92 + 1n -------------> 129I53 + 107X39

Balancing atomic number on both sides, we get

the atomic number of the atom, X = 92 - 53 = 39