Organic

Traps in Organic

• Confuses homologous series and functional groups
  Alkanes CₙH₂ₙ₊₂ (C–C only); alkenes CₙH₂ₙ (C=C); alkynes CₙH₂ₙ₋₂ (C≡C); alkanols R–OH; alkanoic acids R–COOH; esters R–COO–R'. Identify the functional group first.
• Puts a substance or reaction in the wrong class
  Classify from the defining feature: functional group for organic series; bond type and structure for properties; reaction with acid AND alkali for amphoteric. Check each option against the feature, not the name.
• Miscounts atoms, electrons or steps
  After working, check by counting back: total electrons = atomic number; atoms in the formula match the subscripts; number of half-lives = time ÷ half-life.
• Confuses tests for gases
  CO₂ turns limewater milky; H₂ gives a 'pop' with a lighted splint; O₂ relights a glowing splint; NH₃ turns damp red litmus blue; Cl₂ bleaches damp litmus.
• Acid–base definition errors
  Brønsted–Lowry: acid = proton donor, base = proton acceptor. STRONG = fully ionised; CONCENTRATED = much solute per dm³. A dilute strong acid is still strong.
• Takes one factor as the whole answer
  Ask whether the option is necessary or sufficient. If the stem involves two changes or two conditions, both must appear in the answer.