One of the most challenging. Options B and C were more popular than the correct answer; “halogen” made option C incorrect.

Fewer than half answered correctly. Option C most common wrong. Reactions involve movement of electrons, not protons.

Stronger candidates did well; many others chose B—misunderstanding bonding in chlorine or the meaning of “pair”.

About one-third correct. Option B describes graphite’s structure but not why it is used as an electrode.

Over a third chose B. Recall the full name: the hydrogen–oxygen fuel cell.

Listed among the least demanding questions overall.

Poorly answered; >? chose C. Confusion over terms: hydrated = with water; anhydrous = with no water.

Small majority correct; some guessing. Recognise an alkaline gas is produced ? think ammonia from an ammonium salt.

Many candidates appeared to be guessing.

Listed among the least demanding questions overall.

Not well answered. Many couldn’t recall reactions of metals with water or dilute acid. C chosen by >?; B chosen often too.

Order of reactivity not determined by many; response distribution suggests guessing. Metals react more vigorously with steam/dilute acid than cold water.

Listed among the least demanding questions overall.

Most common response was B (incorrect). Yeast is a catalyst, not a reactant; catalysts are not used up and shouldn’t appear as reactants.

Listed among the least demanding questions overall.

Listed among the least demanding questions overall.

Challenging: many chose D by counting ‘red’ spots without checking if they represented the same or different dyes.

Weaker candidates chose A/D which would form a pure salt only if salt and water were the only substances. Here the outcome is a mixture of salt and sand.