Question detail

What is the general formula for alkenes?

Try the question, check the answer, then read the explanation to understand the curriculum point.

Show answer Topic hub Objective page

At a glance

MCQ

Type

practice

Style

Topic

Reactions of alkenes and alcohols (chemistry only)

Question

A. C_nH_2n
B. C_nH_2n+2
C. C_nH_n
D. C_nH_2n-2

Answer

The correct option is C_nH_2n.

Explanation

The correct option is C_nH_2n. C_nH_2n is correct because it directly supports the approved learning objective to relate the repeating unit to the monomer. This belongs to Polymerisation and naturally occurring polymers within Reactions of alkenes and alcohols (chemistry only), so the answer must use the correct organic chemistry context. The other options are incorrect when they confuse the organic family, formula type, reaction condition, product, or property being tested. Keep molecular formula, structural formula, displayed formula, and general formula distinct. Do not confuse alkanes with alkenes, saturated with unsaturated, cracking with combustion, polymers with monomers, or hydrocarbons with oxygen-containing alcohols and carboxylic acids. When formulae are used, preserve the stored notation exactly and explain the GCSE chemistry idea in words rather than using unsupported displayed-formula diagrams.

Common mistake

Confusing Repeating Units

Students often confuse the repeating unit of a polymer with the original monomer, thinking they are the same.

Remember that the repeating unit is derived from the monomer but may not be identical; it reflects the structure of the monomer without any small molecules lost during polymerisation.

Related flashcards

Flashcard 1 of 5

Press Space to flip, arrows to move