How this paper is scored
Thirty questions. Four marks for a correct answer, one mark deducted for a wrong one, nothing gained or lost for a question left blank. The paper is out of 120 marks. A student who gets 24 right and 6 wrong scores out of 120.
The deduction decides how a doubtful question should be handled. A blind guess between four options wins 4 marks a quarter of the time and loses 1 mark three quarters of the time, an average of marks — too little to pay for the seconds it costs. Strike out one option and the same guess averages marks. Strike out two and it averages . Guess after eliminating, never before.
Time budget
Thirty minutes for the whole set, which is the examination pace of about a minute a question. Twenty-five of those minutes are answering and five are review. The 23 single-answer recall and one-step prediction items should take about 40 seconds each, which is roughly 15 minutes; the 4 assertion-reason items at about 75 seconds and the 3 match-the-column items at about 90 seconds add about 10 minutes more. The five minutes left at the end are for the items marked to revisit. A hydrocarbon question that runs past 90 seconds is a question where the reagent was not recognised, and the mark is better spent elsewhere.
What the paper tests
This set is weighted the way the chapter is weighted in the examination: 5 items on the named reactions in both directions, reagent to product and product to reagent; 4 on the distinguishing tests and the exact observation each one gives; 5 on Markovnikov, Saytzeff and the major product; 3 on ozonolysis, forwards from the alkene and backwards from the carbonyl fragments; 4 on hybridisation, bond length, bond angle and the acidity order; 4 on aromaticity, the structure of benzene and the directive influence table; 3 on alkane properties, conformations and halogenation; and 2 on uses, toxicity and carcinogenicity. Almost every answer is a remembered reagent, condition, observation or order rather than a derivation, and the few that need reasoning need one step of it — which carbocation is more stable, which alkene is more substituted, which fragment carries which carbonyl.
Key Point: The condition is examined as hard as the product. Alcoholic potassium hydroxide eliminates and aqueous potassium hydroxide substitutes; Lindlar gives cis and sodium in liquid ammonia gives trans. Marks are lost on the reagent line far more often than on the chemistry.
What is allowed
Pen and rough paper only. No calculator, and no log tables. Nothing in this chapter needs either — every number in it is a recalled bond length, bond enthalpy, temperature or pi-electron count, and the only arithmetic is counting carbons, hydrogens and pi electrons, which is done in the head.
[NEET] Four items use the assertion-reason format and three are match-the-column. Read the reason on its own first, decide whether it is true as a sentence, and only then ask whether it causes the assertion. A true reason sitting beside a true assertion is the commonest trap in the format.