"Science — Materials of Daily Use" — Practice

Question 1

Which of the following is a natural animal fibre?
(a) Nylon  (b) Rayon  (c) Wool  (d) Polyester

Accepted Answer

Wool is sheared directly from the fleece of sheep and other animals, making it a genuine natural animal fibre.

Answer: (c) Wool. Trap (a) Nylon is fully synthetic, made entirely from petrochemicals with no natural raw material. Trap (b) Rayon is semi-synthetic — its cellulose source (wood pulp) is natural, but it is chemically processed into fibre, so it is often wrongly assumed to be fully natural. Trap (d) Polyester is fully synthetic, used in fabrics and PET bottles.

Question 2

The process of separating jute fibres from the stem of the jute plant, by allowing the stem to rot in water, is called:
(a) Ginning  (b) Retting  (c) Scouring  (d) Reeling

Accepted Answer

Retting specifically uses controlled rotting in water to break down the stem tissue surrounding jute fibres, freeing them for extraction.

Answer: (b) Retting. Trap (a) Ginning is the mechanical process of separating cotton fibres from cotton seeds, unrelated to jute. Trap (c) Scouring is cleaning wool of grease and dirt after shearing. Trap (d) Reeling is unwinding silk fibre from a cocoon — all three name real processes from this chapter, but for different fibres entirely.

Question 3

Which of the following is an example of a chemical change?
(a) Melting of ice  (b) Dissolving sugar in water  (c) Rusting of an iron nail  (d) Cutting a sheet of paper into pieces

Accepted Answer

Rusting produces a genuinely new substance, iron oxide, with properties different from iron, and cannot be reversed by ordinary physical means — the defining features of a chemical change.

Answer: (c) Rusting of an iron nail. Trap (a), (b), and (d) are all physical changes — no new substance forms in any of them, even though cutting paper (d) happens to be irreversible in the sense that the original sheet can't be restored.

Question 4

A mixture of sand, salt, and water needs to be separated so that pure water, pure salt, AND sand are all recovered separately. Which sequence of methods achieves this?
(a) Filtration, then evaporation  (b) Filtration, then distillation  (c) Sedimentation, then winnowing  (d) Sieving, then sublimation

Accepted Answer

Filtration first removes the insoluble sand from the salt-water mixture; the filtrate (salt dissolved in water) is then distilled, which condenses and collects the water as it evaporates, so both the pure water and the pure salt (left behind) are recovered.

Answer: (b) Filtration, then distillation. Trap (a) evaporation alone recovers only the salt — the water escapes as vapour into the air and is lost, failing the 'recover pure water too' requirement. Trap (c) applies the wrong methods entirely — winnowing separates grain from husk, not salt from water. Trap (d) sublimation applies to substances like camphor or ammonium chloride that pass directly from solid to gas, not to salt.

Question 5

Threshing, in the agricultural separation of grain, specifically refers to:
(a) Blowing away husk using wind  (b) Beating harvested stalks to loosen grain from them  (c) Passing grain through a sieve  (d) Letting heavier particles settle at the bottom of water

Accepted Answer

Threshing is the step of loosening grain from the stalks it grew on, typically by beating the harvested stalks or running them through a machine, and comes before winnowing in the harvest-to-clean-grain sequence.

Answer: (b). Trap (a) describes winnowing, the step that follows threshing, not threshing itself. Trap (c) describes sieving, a different method used for separating particles by size. Trap (d) describes sedimentation, unrelated to grain processing.

Question 6

Bakelite is used to make electrical switches mainly because, being a thermosetting plastic, it:
(a) Melts and can be reshaped repeatedly when heated  (b) Does not soften on heating once it has been moulded, and is a poor conductor of electricity  (c) Is fully biodegradable within a few weeks  (d) Is a natural fibre with high tensile strength

Accepted Answer

Thermosetting plastics like bakelite are moulded once and remain rigid even under heat afterward, and combined with being a poor electrical conductor, this makes them ideal for switch housings that sit near live circuits and warm appliances.

Answer: (b). Trap (a) describes thermoplastics, the opposite behaviour category. Trap (c) is factually wrong — plastics, including bakelite, are non-biodegradable. Trap (d) confuses a synthetic plastic with a natural fibre, categories from two different parts of this chapter.

Question 7

Two liquids, X and Y, are completely miscible with each other and have different boiling points. The most suitable method to separate them into their pure components is:
(a) Filtration  (b) Sedimentation and decantation  (c) Distillation  (d) Winnowing

Accepted Answer

Distillation separates miscible liquids with different boiling points by evaporating the lower-boiling-point liquid first and condensing it separately, which works precisely because the two liquids vaporise at different temperatures.

Answer: (c) Distillation. Trap (a) filtration only separates an insoluble solid from a liquid, not two liquids from each other. Trap (b) sedimentation and decantation apply to an insoluble solid settling in a liquid, not to two miscible liquids. Trap (d) winnowing applies to separating grain from husk, unrelated to liquid mixtures.

Question 8

A Class VI teacher gives students a mixed box of buttons, marbles, spoons, and pebbles and asks them to sort the objects into groups using their own criteria, before naming any category. This activity primarily supports which pedagogical goal from NCF 2005's approach to early science teaching?
(a) Rote memorisation of a fixed classification scheme  (b) Building the concept of classification inductively, through direct, hands-on sorting experience  (c) Testing students' prior knowledge of chemical formulas  (d) Preparing students for a written definitions test only

Accepted Answer

Letting students generate their own sorting criteria from direct handling of real objects builds classification as a concept through their own reasoning, rather than delivering a ready-made scheme for memorisation — the defining move of NCF 2005's activity-based approach.

Answer: (b). Trap (a) contradicts the inductive, learner-generated purpose of the activity. Trap (c) misapplies an unrelated content area (chemical formulas) to a classification activity. Trap (d) narrows a genuine concept-building activity down to mere test preparation, missing its actual pedagogical purpose.

Question 9

A student says, 'Since melting the wax of a candle needs heat, and burning the same candle's wick also needs heat, both must be chemical changes.' Which teaching response best addresses this misconception?
(a) Agree, since both processes clearly involve heat  (b) Explain that melting wax only changes its physical state and is reversible on cooling, while burning the wick forms new substances and is not reversible — so heat alone does not decide whether a change is physical or chemical  (c) Tell the student that only burning counts as a real 'change' at all, and melting does not  (d) Avoid resolving the disagreement, since both views can be considered equally valid

Accepted Answer

The correct response directly identifies the actual test for a chemical change (whether a new substance forms) and applies it to both examples, correcting the false belief that heat alone determines the category.

Answer: (b). Trap (a) endorses the very misconception the teacher must correct. Trap (c) wrongly denies that melting counts as a change at all — it is a genuine physical change. Trap (d) evades correcting a clearly stated misconception, which a teacher is expected to actively address.

Question 10

While teaching the separation of a sand-water-salt mixture, a teacher has students physically perform filtration and evaporation themselves in small groups, rather than only viewing a labelled diagram in the textbook. This choice best reflects which principle emphasised for science teaching in NCF 2005?
(a) Learning should be centred on textbook diagrams alone, for accuracy  (b) Learning is most effective when abstract processes are made concrete through direct manipulation and observation by the learner  (c) Group activities should generally be avoided in science, to prevent errors  (d) Only the teacher should perform demonstrations, to save classroom time

Accepted Answer

NCF 2005 specifically favours learners physically carrying out a process themselves over passively observing a diagram or a teacher-led demonstration, since direct manipulation makes an otherwise abstract separation process concrete and personally verified.

Answer: (b). Trap (a) and trap (d) both reject the hands-on, learner-centred element that NCF 2005 promotes, defaulting instead to passive or teacher-only methods. Trap (c) invents an unsupported claim that group activity itself is undesirable in science teaching.

Practice — "Science — Materials of Daily Use"

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