From the reaction between Cu and HNO₃, the formed gas is NO₂ instead of NO₃. Hence the correct balanced equation would be,
Cu(s) + 4HNO₃(aq) → Cu(NO₃)₂(aq) + 2NO₂(g) + 2H₂O<span>(l)
Here, Cu goes to </span>Cu(NO₃)₂ by changing its oxidation number from 0 to +2 while NO₃⁻ goes to NO₂ by reducing its oxidation state from +5 to +4 . Hence Cu is oxidized by HNO₃ in the reaction.
The percentage by mass of water in Na2CO3.10H2O from the calculation is 62.9%
<h3>What is percentage by mass?</h3>
The term percentage by mass refers to the amount of a particular moiety by mass in a molecule.
In this case, we know that the molar mass of Na2CO3.10H2O is 286 g/mol the molar mass of the 10 moles of water is 180 g/mol hence the percentage by mass of water in the compound is; 180 g/mol /286 g/mol * 100/1 = 62.9%
Learn more about percentage by mass: brainly.com/question/16885872
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The correct statement to fill the blank would be the first option. Atomic energy is the energy in the nucleus of an atom of electrons and their shells. From the word atomic itself, we can say that this energy is energy within and carried by the atoms.
