How to Use This Paper
Marking scheme. Every question carries for a correct answer and a wrong answer costs , so a blind guess between four options is worth marks on average — very slightly positive, and once you have eliminated even one option guessing is clearly worth it. What actually costs marks is guessing under time pressure on a long calculation you have half finished, where a half-formed number feels like an answer. In the real paper Section B, the numerical-value section, also carries for a wrong answer, so the same guessing arithmetic applies there; every item in this practice set is a four-option multiple-choice question and carries the too, and an unattempted question scores zero either way.
Time budget. Sixty minutes for the thirty questions, an average of two minutes each. That average hides the real spread. The ten oxidation number and classification items should each be finished inside a minute, the five balancing items inside two, and the five electrode-potential items inside a minute apiece. What you save there is what pays for the titration and mixture arithmetic, where three to four minutes on a single question is normal and correct. That is roughly minutes.
What is being tested. The paper runs in six blocks in the order the chapter builds them: six questions on oxidation number, with the peroxide linkage and the fractional values doing most of the damage; four on sorting a reaction into its type, including disproportionation and its mirror image; five on balancing, asked for a single coefficient, an electron count or a sum of coefficients; six on n-factor, equivalent mass, normality and titration arithmetic; four on mixtures, back titration and double titration; and five on electrode potentials, cell EMF, spontaneity and the free-energy weighting that combines two half reactions. The long items are the ten in the middle, roughly questions 16 to 25 — every one of them is a multi-step calculation, and every one of them has a distractor waiting for a wrong n-factor. If time runs short, leave those for the end and bank the quick marks first.
Allowed in the hall. No periodic table and no data booklet are supplied — only rough sheets. No calculator. Log tables are not available, so every calculation here has been built to come out on plain arithmetic. Every molar mass a calculation needs is stated inside the question that needs it.