Exactly how many chromosomes we are talking about depends on the species. A mosquito has 6 chromosomes, a pea plant has 14, a sunflower 34, a human being 46, and a dog 78. Closely related species tend to have a similar number of chromosomes.
The substance must be able to alter its physical characteristic (for example, its color) in accordance to a change in pH. One example of this is litmus paper, which becomes red under acidic conditions and blue under basic conditions.
The southern portion of the region has the highest rates of HIV/Aids.
I hope this helps.