How to calculate the mass percent of hydrogen

divide the mass of element in 1 mole of the compound by the compound's molar mass and multiply the answer by 100.

Explanation:

take the molar mass of hydrogen in the water molecule, divide by the total molar mass of water, and multiply by 100.

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The definite shape and volume of solids can be explained on the basis of kinetic theory of matter. In case of solids the kinetic energy of the molecules is least and the force of attraction between the molecules is maximum. The molecules of the solids can just vibrate about the mean positions, but cannot migrate from one position to another, because the intermolecular forces are very strong,and, they have the least Kinetic forces, having most potential forces. Thus solids have a definite shape and definite volume