Which one has the greatest mass, Hg or Co?

Asample of tin (ii) chloride has a mass of 0.49 g. after heating, it has a mass of 0.41 g.  what is the percent by mass of water in the hydrate?   %

How many grams of ammonia would be produced by the decomposition of 16.93 mlof hydrazine? (the density of hydrazine is 1.021g/ml)

The plant food contains nh4)3po4 what tests would you run to verify the presence of the nh4 ion and the po4 ion