Sodium (Na) has a +1 charge and Iodine ( I ) has a -1 charge. To create a molecule of sodium iodide the charges will need to balance.
Because the charges on anion and cation are the same; the molecular formula will be NaI
Mass divide by volume
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Hydrazine is a mixed chemical...look up what is in Hydrazine. Then find the chemicals in it. 13.00g of hydrazine can react to anything....water, gas, etc. but it might not be visible.