To know the density you also need to know the volume of the rock.
Scientists use carbon-14 to date ancient fossils.
Plants and animals absorb carbon-14 produced by cosmic rays. The ratio of C-14 to C-12 is constant when they are alive.
When they die, the C-14 decays to C-12, and the ratio changes.
Carbon-14 has a half-life of 5730 years. Thus, the object loses half its C-14 every 5730 years.
Scientists can use the C-14 to C-12 ratio to date fossils up to 70 000 years old.
The Ph of tomato juice is calculated as follows
Ph = -log (H+)
if H+ ion concentration is 10^-4
Ph is therefore = -log (10^-4) =4
the tomato juice has a Ph of 4
