Matter

Traps in Matter

• Confuses elements, compounds and mixtures
  Element: one kind of atom. Compound: elements chemically combined in fixed proportions, new properties (water, NaCl). Mixture: components not chemically combined, variable composition, separable physically (air, sea water, brass).
• 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.
• Uses everyday or macroscopic thinking instead of particles
  Ask what the particles, ions or electrons are doing. Properties of a substance come from its particles and bonds, not from how it looks or feels.
• Reverses a trend, direction or effect
  State the rule with its direction before looking at the options (down group 1 reactivity INCREASES; exothermic forward reaction: heating shifts LEFT). An option that is the mirror image of the rule is the trap.
• Mixes up a pair of similar chemical terms
  Keep a list of confusable pairs with one defining feature each and a hook. Underline the key word in the stem and check it against the definition, not the sound of the name.
• Picks a related substance or process with a different role
  Learn reagents and processes as one-line 'name → job' cards and contrast neighbours in a table (process | product | catalyst | conditions). Match the job in the stem, not just the topic.
• Confuses laws of chemical combination
  Conservation of mass: mass unchanged in a reaction. Definite proportions: a compound always has the same composition. Multiple proportions: masses of one element combining with a fixed mass of another are in simple ratios (CO, CO₂). Gay-Lussac: gas volumes in simple ratios.
• 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.
• Chooses a true but irrelevant statement
  Re-read the question word (why, which, what causes). A true fact that answers a different question is still wrong.