What happens to the potential energy of a book that is dropped from a desk to the floor? A.
It gains mass.

B.
It stays the same.

C. It increases as the book falls.

D.
It is converted into kinetic energy.

D.   It is converted into kinetic energy.

Explanation:

When a book is dropped from a desk to the floor, the potential energy of the book is converted to kinetic energy as it falls.

Potential energy of a body is the energy due to the position of the body. At a particular height, the potential energy is maximum. A body with mass and moving with velocity will have kinetic energyAs the book drops through the height, to conserve energy, the potential energy is converted to kinetic energy.

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.