The reasoning section of an NSO paper does not test new science — it tests whether you can spot the RELATIONSHIP or RULE connecting facts you already know.
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A science analogy asks for the SAME relationship, using science facts instead of everyday words.
📌 Solving a science analogy
Turn the first pair into a sentence: "Nucleus : Control centre" becomes "The nucleus IS THE control centre of the cell."
Apply the exact same sentence pattern to the second pair: "Mitochondria : ______" becomes "Mitochondria IS THE ______."
For classification, find the odd one out by naming the group first, then checking which item breaks the rule.
✨ Worked examples
Analogy
same relationship
Nucleus : Control centre :: Mitochondria : Powerhouse
Classification
find the odd one out
Oxygen, Nitrogen, Water, Hydrogen → Water (the only compound, not an element)
A science-based series or code needs the same method as a normal one — just applied to units, formulae or the periodic table.
📊 Science series to recognise
| Series | Rule | Next |
|---|---|---|
| 2, 4, 8, 16, … | each term doubles (like repeated cell division) | 32 |
| H, He, Li, Be, … | atomic numbers increase by 1 (periodic table order) | B (boron, atomic number 5) |
| 1, 4, 9, 16, 25, … | the square numbers | 36 |
Coding trick: if a code uses letter positions (A=1, B=2, … Z=26), always verify the rule on at least TWO letters before trusting it on the rest of the word — one matching letter could just be a coincidence.
A cause-effect question gives you two statements and asks how they are related — this is different from simply recalling a fact.
🏆 Judging cause and effect
Both statements true, and one explains the other — the first is usually the cause, the second the effect.
Both true, but unrelated — two correct facts that do not explain each other.
One statement is false — check every fact carefully before assuming a link exists.
Pro tip: never assume a cause-effect link just because two true statements are placed next to each other — verify the actual scientific mechanism connects them.
12 NSO-pattern reasoning questions built on science content, including two Achievers-level questions.
