Question

11. An isolated 8Be atom will spontaneously decay into two alpha particles. What can be concluded about the mass of the 8Be atom?

A. The mass is less than double the mass of the 4He atom

B. The mass is exactly double the mass of the 4He atom.

C. The mass is greater than double the mass of the 4He atom.

D. None of the above may be concluded.

12. In a nuclear reaction the mass of the products is less than the mass of the reactants. This is not observed in a chemical reaction. Why not?

A. Mass is conserved in chemical reactions, which involve only the electromagnetic force.

B. The mass deficit in chemical reactions is too small to be observed by present techniques.

C. In chemical reactions, the mass deficit is balanced by a mass surplus.

D. In chemical reactions, the mass is held constant by gravity

2. What is the half-life of a radionuclide if 1/16 of its initial mass is present after 2 hours?

1. 15 min
2. 30 min
3. 45 min
4. 60 min

1. Some isolated ²³⁵U atoms will spontaneously fission into two approximately equal-sized fragments. The following represents a possible reaction:

²³⁵ U®¹⁴¹Ba+⁹²Kr + ?            

What is missing from the right side of the reaction?

1. A proton.
2. A neutron.
3. A proton and a neutron.

D.Two neutrons

Answer 1