Question

hydrogenation is the addition of ______ to an alkene.
○ hydrogen (h)
○ hydrogen gas (h₂)
○ hydroxide (-oh)
○ water (h₂o)
○ hydrogen peroxide (h₂o₂)
question 3 (10 points)

Explanation:

Hydrogenation is a chemical reaction where hydrogen gas ($\ce{H_2}$) is added to an unsaturated compound like an alkene, typically in the presence of a catalyst, to form a saturated compound (alkane). Hydrogen (H) is an atom, hydroxide (-OH) is a functional group, water ($\ce{H_2O}$) and hydrogen peroxide ($\ce{H_2O_2}$) are different compounds and not involved in hydrogenation of alkenes in the typical sense. So the correct option is hydrogen gas ($\ce{H_2}$).

Answer:

B. hydrogen gas ($\ce{H_2}$) (assuming the second option is labeled B; if the original labels are different, adjust the label accordingly with the text "hydrogen gas ($\ce{H_2}$)")