Answer : The mole ratios of Hydrazine to Hydrogen peroxide is 1 : 2 and
the mole ratios of Hydrazine to water is 1 : 4.
Explanation :
The balanced chemical equation is,

According to the given reaction,
1 mole of Hydrazine react with the 2 moles of Hydrogen peroxide.
Therefore, the mole ratios of Hydrazine to Hydrogen peroxide is 1 : 2
And in case of Hydrazine and water,
1 mole of Hydrazine gives 4 moles of water.
Therefore, the mole ratios of Hydrazine to water is 1 : 4
Not sure how they're connected to atmosphere other than polluting it with hot ash, but im fairly certain it creates land masses which separate oceans and form land underwater with certain underwater volcanoes
Explanation:
In first one it should be 2Mg
and in second = 2Mgo
hope it helps....
The percentage by mass of oxygen in the compound
find the total mass=( 1.900+ 0250 +0.850) = 3
the percentage mass mass of oxgyen/total mass x100
that is (0.850/3) x100=28.33%