Atomic and Nuclear Physics Answers

1. Jamie wanted to find the approximate mass of a bag of rice using a plank and metal weights. She placed the bag of rice on one of the plank`s end and an empty box on the other end. She balanced the plank by filling the box with 25 pieces of metals weights, each weighing 4.4 lbs. What is the mass in kg of the bag of rice? (ANSWER IN G.R.E.S.A.)

a.     Boron 10 has an atomic number of 5 and a nuclear mass of 10.01294 u. Calculate the binding energy per nucleon for a boron 10 atom in MeV.         

      The mass of a proton is 1.00728 u and the mass of a neutron is 1.00867 u.

b.    Boron 10 can be produced in two different ways:

(1)  By a single beta minus decay from beryllium 10

(2)  By a single beta plus decay from carbon 10.

Carbon 10 has a nuclear mass of 10.01685 u and beryllium 10 has a nuclear mass of 10.01353 u.

Explain which beta particle would have the highest velocity.  

Initially the sample contained 2.0 g of the radioactive isotope. Calculate the number of radioactive nuclei in the sample after 210 seconds.

The number of nuclei in 262 g of dubnium is 6.02 x 10²³

(decay constant: 0.02s-1)

a.     Boron 10 has an atomic number of 5 and a nuclear mass of 10.01294 u. Calculate the binding energy per nucleon for a boron 10 atom in MeV.         

      The mass of a proton is 1.00728 u and the mass of a neutron is 1.00867 u.

b.    Boron 10 can be produced in two different ways:

(1)  By a single beta minus decay from beryllium 10

(2)  By a single beta plus decay from carbon 10.

Carbon 10 has a nuclear mass of 10.01685 u and beryllium 10 has a nuclear mass of 10.01353 u.

Explain which beta particle would have the highest velocity.  

A force of 14 N causes an object to accelerate at 2 m/s2.

Determine the mass of the object.

A few days before the Christmas of 1898, Pierre Curie scrawled the word 'radium' in his notebook as the name for a new element he and his wife Marie had discovered in their laboratory in Paris. Radium is a brilliant white, luminescent, rare and highly radioactive metallic element. They used the radiation emitted from radium 226 to define the unit the curie (Ci). 1 curie = 3.7 x 10¹⁰ decays per second.

a.     A sample of 3.2 x 10²² radium 226 atoms have an activity of 12 Ci. Determine the decay constant for radium 226.    

b.     Radium 226 is a solid at room temperature and it decays to radon 222 which is a colourless and odourless radioactive gas at room temperature. Radon 222 has a half life of 3.8 days and also decays via alpha decay. 

Compare the dangers of exposure to samples of radium 226 and radon 222, assuming each sample initially has the same number of atoms of each element.  

c.     During the decay of radium 226, nuclear equilibrium of radon 222 can occur at which the rates of production and decay of radon 222 are equal. 

(i)             What does this tell you about the number of radon 222 atoms at any point in time?  

(ii)            Determine the number of radon 222 atoms that must be present in the sample in part (a) for this nuclear equilibrium to occur.

Leonard decides to create 5.0 g of the artificial element neptunium 236. The element is radioactive with a half life of 1.5 x 10⁵ years.

a.     What is meant by an “artificial element”?  (1)

b.     Calculate the initial activity of the neptunium 236 sample. The number of nuclei in 236 g of neptunium are 6.02 x 10²³. (3)

c.     Neptunium 236 has three possible decay modes which are shown in the table below. The products of each type of decay are also shown.

Identify the mystery nucleus (represented by the question mark) in the following

reaction:

1 0 n + 235 92 U 144 56 Ba + ? + 2 1 0 n

A nucleus has 25 protons and 30 neutrons. What is the symbol for this nucleus?