. Find the mass of 2.61 moles of H2O2.

Mass of H₂O₂ = 88.778 g

The mole itself is the number of particles contained in a substance amounting to 6.02.10²³  

Mole can also be determined if the amount of substance mass and its molar mass is known

moles of H₂O₂ = 2.61

So the mass of H₂O₂(MW=34,0147 g/mol) :

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.