Final answer:
The correct answer is (c) which states that an alkyne has the general molecular formula CnH₂N-2. Alkynes have triple bonds and are unsaturated hydrocarbons, which can be transformed into alkanes through catalytic hydrogenation.
Step-by-step explanation:
The question pertains to alkynes, which are a class of hydrocarbons with specific structural and chemical properties. Answering the multiple-choice question:
(c) has general molecular formula CnH₂N is the correct option for alkynes. This is because alkynes have a triple covalent bond between at least two carbon atoms, and their general formula for non-cyclic, non-branching alkynes is
CnH₂n-2, which accounts for the fewer hydrogen atoms compared to alkanes, given the same number of carbon atoms. The simplest alkyne is ethyne, frequently called acetylene, with the formula C2H2. Therefore, (a) is incorrect since alkynes are not saturated hydrocarbons.
(b) is also incorrect because alkynes typically undergo addition reactions rather than substitution reactions due to their triple bonds. (d) is correct in that alkynes can be transformed into alkanes via catalytic hydrogenation, which adds hydrogen to the triple bond converting it to a single bond.