CU is the element symbol for Copper.
One mole of a substance is defined by Avogadro as consisting of 6.022 x 1023 atoms. This is Avogadro's number. To calculate the number of atoms in two moles of sodium, use dimensional analysis. 2.0 moles Na x 6.022⋅1023g1mol=1.20⋅1024 atoms of Na
Answer:

Explanation:
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In this case, since the average rate of reaction is computed as a change given by:
![r=\frac{\Delta [NH_4NO_2 ]}{\Delta t}](https://tex.z-dn.net/?f=r%3D%5Cfrac%7B%5CDelta%20%5BNH_4NO_2%20%5D%7D%7B%5CDelta%20t%7D)
In such a way, given the concentrations at the specified times, we plug them in to obtain:

Whose negative sign means the concentration decreased due to the decomposition.
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The empirical formula for a compound is KClO3
Explanation
find the moles of each element
moles = % composition/molar mass
molar mass of of potassium =39g/mol ,chlorine = 35.5 g/mol, oxygen =16 g/mol
moles of potassium = 31.9 / 39 = 0.818 moles
moles of chlorine = 28.9/35.5 = 0.814 moles
moles of oxygen = 39.2/ 16 = 2.45 moles
find the mole ratio by dividing with the smallest mole = 0.814 moles
potassium = 0.818/0.814 =1
chlorine = 0.814/0.814 = 1
oxygen = 2.45 /0.814 =3
the empirical formula is therefore = KClO3