4. An impatient student does not wait for all the iodine to react. Subsequently, the remaining iodine sublimes away during the product isolation step. Will the calculated mass ratio for the product, g I/g Zn, to be higher or lower than the correct value? Explain.

Higher

Explanation:

It looks as if you prepared zinc iodide by the reaction of zinc with iodine.

Your procedure was probably something like this:

You know the mass of iodine used, so you can get the mass of zinc by difference.

For example, assume you measured out 0.5 g of I₂ and got 0.6 g of ZnI₂ as product. You would assume it contained 0.5 g of I₂ and 0.1 g of Zn. Your calculated mass ratio would be I₂/Zn = 5/1.

The impatient student loses 0.1 g of I₂ by sublimation, so they get only 0.55 g of ZnI₂. However, they still think it contains the original 0.5 g of I₂, and they determine the mass of Zn to be 0.05 g. Their calculated mass ratio is I₂/Zn = 0.5/0.05 = 10/1.

If some of the iodine sublimes away, the calculated value for the mass ratio will be higher than the correct value.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.