1. how many grams is 3.87 mol mg?

0.948g

Explanation:

Atomic mass of  Mg is 24.305

1 mole of Mg is therefore 24.305 g

0.039 moles will weigh 0.039 x 24.305 g/mole = 0.948 g

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: