The answer is 4. pH= -log10 [H3O+]
1)Left to right in a period it goes up by one
2) the number valence electrons are the same from top to bottom
The definition of mechanical power is
Power = (work done) / (time to do the work).
From that definition, it looks pretty much like the power of a machine
depends on work and time.
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure, that occurs naturally in pure form.
hope this helps