Why is a roman numeral needed for iron compounds but not for compounds containing magnesium?

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.

Which one of the following substances would be the most soluble in ccl4? na2so4 h2o ch3ch2ch2ch2oh c4h10 hi

Asuspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. if one wishes to follow this process by monitoring the release of 14co2, at which positions in the glucose molecule would the 14c label need to be incorporated?