How many ions that have a +1 charge will bond with an ion that has a –2 charge?

one

two

three

four

In order to form a neutral which means zero-charged compound, the sum of the charges of the atoms should be zero. Let x be the number of +1-charged atom, the equation generated is 
 
                                 (+1)(x) + (-2) = 0

From the equation, the value of x is 2. Thus, 2 ions with +1 charge should be combined with an ion with -2 charge.

29.1-12=17.1the answer is this one

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