(A) Metal oxides are basic in nature. (B) Air expands on heating. (C) Lime…
2024
(A) Metal oxides are basic in nature.
(B) Air expands on heating.
(C) Lime water turns milky on passing carbondioxide.
(D) Sodium hydroxide and hydrochloric acid neutralise each other.
If observation is represented by O and inference by I, which of the following statements is correct?
Answer: C. O - C; I - A, B, D — Observation is a fact perceived directly through the senses (or an instrument) as an event happens — a raw, first-hand description of what was seen, heard, or…
- A.
O - C, D; I - A, B
- B.
O - B, C; I - A, D
- C.
O - C; I - A, B, D
- D.
O - A, B; I - B, C
Attempted by 3 students.
Show answer & explanation
Correct answer: C
Observation is a fact perceived directly through the senses (or an instrument) as an event happens — a raw, first-hand description of what was seen, heard, or measured. Inference is a conclusion reached by reasoning about such facts — a generalisation, rule, or interpretation that goes beyond what was witnessed in that single instant.
Applying this test to each statement in turn:
(A) 'Metal oxides are basic in nature' is a general chemical rule built up from testing many metal oxides, not a report of one witnessed event — an Inference.
(B) 'Air expands on heating' is likewise a general physical law drawn from repeated heating trials, not a single sensory report — an Inference.
(C) 'Lime water turns milky on passing carbon dioxide' describes exactly what is seen happening in this one experiment — a direct visual change — an Observation.
(D) 'Sodium hydroxide and hydrochloric acid neutralise each other' names a reaction type (neutralisation); recognising it as such needs chemical reasoning about what reacted with what, not a raw sensory report — an Inference.
So exactly one statement, C, is an Observation, and the other three — A, B and D — are Inferences, matching the grouping that places O against only C and I against A, B and D.
Checking the other groupings against this same test:
The grouping that places the acid–base reaction description (D) alongside C as an observation overlooks that naming a reaction 'neutralisation' needs chemical reasoning about the products — that classification step makes it closer to an inference than a raw sensory report.
The grouping that places 'air expands on heating' (B) alongside C as an observation overlooks that this is a general physical law drawn from repeated trials, not a one-off sensory report.
The grouping that lists 'air expands on heating' (B) under both categories at once is self-contradictory — a single statement cannot be simultaneously a direct observation and a reasoned inference, regardless of how the remaining letters are placed.
This matches the CTET July 2024 Paper-II official answer key for this item.