The atomic weight of H is 1, O is 16.
There are two of each in a hydrogen peroxide molecule.
(1*2)+(16*2)=2+32
2+32=34
The weight of the whole molecule is 34, and hydrogen makes up 2 of that.
(2/34)*100=0.0588235294*100
0.0588235294*100=5.88235294
The percentage mass of hydrogen in a hydrogen peroxide molecule is 5.88%
The one that does not demonstrates the law of conservation of matter would be the third option: 
<h3>What is law of conservation of matter? </h3>
It is a law that explains that matters are conserved during the course of chemical reactions. They can neither be destroyed nor created.
Thus, the number of moles of the species in a reaction remains the same before and after the reaction.
Thus, an equation that demonstrates the law of conservation of matter will be balanced in terms of the number of moles of species.
The only equation, in this case, is 
There are 3 oxygen species on the reactant while 5 are present on the product side.
More on the law of conservation of matter can be found here: brainly.com/question/9434062
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CH3NH2 can only have as many hydrogen bonds as hydrogen bonding sites in the molecule. CH3NH2 has two N−H bonds and a lone pair of electrons on the nitrogen atom. Therefore, CH3NH2 can form three hydrogen bonds with water.
<h2>
Answer:</h2>
The physical and chemical properties of seawater vary according to latitude, depth, nearness to land, and input of fresh water. The physical and chemical properties of seawater have a great effect on organisms, varying especially with the size of the creature. Marine organisms have evolved a wide variety of unique physiological and morphological features that allow them to live in the sea.
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Molar mass :
HC₂H₃O₂ = 1 + 12*2 + 1 * 3 + 16 * 2 = 60 g/mol
1 mole <span>HC₂H₃O₂ -------------- 60 g
</span>1.26x10-⁴ mole ----------------- mass
mass = 1.26x10-⁴ * 60
mass = 0.00756 g of <span>HC₂H₃O₂</span>
hope this helps!