What has the study or fossils allowed scientists to do ?

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

If 15 drops of ethanol from a medical dropper weight 0.60g, how many drops does it takes from a dropper to dispense 1.0ml of ethanol? the density of ethanol is 0.80g/ml

Nh4no3 n2o + 2h2o a chemist who is performing this reaction starts with 160.1 g of nh4no3. the molar mass of nh4no3 is 80.03 g/mol; the molar mass of water (h2o) is 18.01 g/mol. what mass, in grams, of h2o is produced?