How many leaders does a democracy have?

What artifact did modern scholars study to them understand hieroglyphics

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal

Human beings spread all around the world over a period of millions of years. identify when humans arrived in different regions of the world. 200,000 years ago 100,000 years ago 40,000 years ago 30,000 years ago