1. is 7,9-di-tert-butyl-1-oxaspiro[4,5]de ca-6,9-diene-2,8-dione toxic? and why 2. is 2-(2-butoxyethoxy)ethoxy , TMS derivative toxic and why?
3. is pentasiloxane, dodecamethyl toxic and why?

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

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.