What occurs when cr^3+ ions are reduced to cr^2+ ions?

a) electrons are lost and the oxidation number of chromium increases

b) electrons are lost and the oxidation number of chromium decreases

c) electrons are gained and the oxidation number of chromium increases

d) electrons are gained and the oxidation number of chromium decreases

D:

When electrons are gained, the charge of the atom decreases.

When you are given an atom with a charge, the oxidation of that atom is the charge. So by going from a Cr^3+ (Oxidation Number = 3) to a Cr^2+ (Oxidation Number = 2), the Oxidation Number thus decreases.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later