physical-changes MCQs for UPSC Prelims

28 practice questions on physical-changes from the Changes Around Us: Physical and Chemical section of the UPSC Prelims syllabus. 28 come with a written explanation. Try the sample set below - the answer stays hidden until you ask for it.

8 Easy 14 Medium 6 Hard

Sample questions

Q1
medium

An aluminium sheet is cut and pressed into a lunch box. Which statement best describes this change?

  1. A A chemical change, because a useful new object is made
  2. B A change of state from solid to liquid
  3. C A change of state from liquid to solid
  4. D A change of shape and size only, as the metal is still aluminium
Show answer and explanation

Correct answer: D - A change of shape and size only, as the metal is still aluminium

Cutting and pressing alter the form of the sheet, but every property of the metal remains that of aluminium. The metal stays solid throughout, so neither of the change-of-state options can apply. Making a new object is not the same as making a new substance, which is what a chemical change requires.

Q2
easy

A sheet of paper is folded several times to make a paper boat. What has changed?

  1. A The material, from paper to plastic
  2. B Only its shape and size, not the material
  3. C The chemical nature of the paper
  4. D Nothing at all
Show answer and explanation

Correct answer: B - Only its shape and size, not the material

Folding rearranges the sheet but leaves it as the same piece of paper, so only the shape and the space it takes up have changed. Paper cannot turn into plastic by folding, and its chemical nature is untouched. Saying nothing changed ignores the obvious change of shape.

Q3
medium

Steam from a boiling kettle is led through a cold glass tube, and clear water collects at the far end. What does this experiment show?

  1. A Boiling and condensing are physical changes, because the water is recovered unchanged
  2. B Water is destroyed when it is boiled
  3. C Boiling is a chemical change that condensing reverses
  4. D Steam is a new substance produced from water
Show answer and explanation

Correct answer: A - Boiling and condensing are physical changes, because the water is recovered unchanged

The liquid collected is ordinary water again, so nothing new was made at any stage and both boiling and condensing are physical. Steam is simply water in the gaseous state, not a different substance. Water is not destroyed; it merely changes state. A chemical change would not give back the starting substance so easily.

Q4
easy

A stick of white chalk is crushed into a fine powder. What has happened to the chalk?

  1. A It has changed into a completely new substance
  2. B Its size and look have changed, but it is still chalk
  3. C It has joined with air to make a new powder
  4. D It has turned into a liquid
Show answer and explanation

Correct answer: B - Its size and look have changed, but it is still chalk

Crushing breaks the stick into smaller bits, so only the size and appearance change. The powder still has the properties of chalk, so no new substance has been made and nothing has combined with air. The powder is a solid, not a liquid.

Q5
medium

A goldsmith melts an old gold ring and casts the metal into a chain. Which observation shows that no new substance was formed?

  1. A The metal in the chain is still gold, with the same shine and density
  2. B The chain looks quite different from the ring
  3. C The gold became soft while it was hot
  4. D Heating was needed to melt the ring
Show answer and explanation

Correct answer: A - The metal in the chain is still gold, with the same shine and density

Sameness of the substance is shown by the properties staying the same, and the chain is still gold with gold's shine and density. Looking different, needing heat, and turning soft all happen in many chemical changes too, so none of them can prove that the substance is unchanged.

Q6
hard

Two beakers each hold $200\ \text{g}$ of water. Beaker P is cooled until the water freezes solid. Beaker Q is heated until all the water boils away, and the steam is collected and cooled. Which statement is correct?

  1. A Only the change in P is physical
  2. B Both are chemical changes, since heat was involved
  3. C Only the change in Q is physical
  4. D Both are physical changes, since water is obtained back in each case
Show answer and explanation

Correct answer: D - Both are physical changes, since water is obtained back in each case

Freezing gives ice that melts back to the same water, and boiling gives steam that condenses back to the same water, so neither beaker produces a new substance. Both changes are therefore physical, which rules out the two options that pick only one of them. Heat being added or removed does not decide whether a change is chemical.

Q7
medium

A blacksmith heats an iron rod till it glows red, hammers it into a hook and cools it in water. The hook is still iron. Which change has taken place?

  1. A A chemical change, because water was used at the end
  2. B A chemical change, because the iron glowed red
  3. C A change of state, because the iron melted
  4. D A change of shape, which makes it a physical change
Show answer and explanation

Correct answer: D - A change of shape, which makes it a physical change

The hook has a new shape but is still the same iron, so the change is physical. Glowing red only shows that the metal is very hot; it does not mean a new substance appeared. Dipping the hot iron in water cools it without producing anything new. The iron softened but never melted into a liquid.

Q8
medium

Aarav beats a copper wire flat with a hammer until it becomes a thin sheet. He claims a new substance has formed. Why is he wrong?

  1. A The sheet is still copper and has all the properties of copper
  2. B Copper cannot be beaten into a sheet at all
  3. C Hammering does nothing, so no change has taken place
  4. D A new substance can form only when a solid is heated
Show answer and explanation

Correct answer: A - The sheet is still copper and has all the properties of copper

The flattened sheet still shines like copper, conducts like copper and weighs the same, so the substance is unchanged. Copper is malleable, which is exactly why it can be beaten into sheets. New substances can form without heating, as in rusting. A change of shape has certainly happened, so saying nothing changed is also wrong.

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