Pure Substances — Homi Bhabha Class 6 Chemistry MCQs with Solutions
Free Homi Bhabha Class 6 Chemistry Pure Substances MCQs with step-by-step solutions (10 questions). Part of Substances & Their Composition. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Pure Substances · easy · theory
Which of these is a pure substance?
A. Milk
B. Garden soil
C. Lemonade
D. Distilled water ✓ Correct
Solution: Distilled water is made of only one kind of particle (H₂O), so it is a pure substance. Lemonade, soil and milk are mixtures of many things.
Q2 — Pure Substances · easy · theory
A pure substance is made up of only one kind of ______.
A. shape
B. colour
C. size
D. particle ✓ Correct
Solution: A pure substance contains only one kind of particle throughout, which gives it the same composition everywhere.
Q3 — Pure Substances · easy · theory
Which of the following is a pure substance?
A. Air
B. Vegetable soup
C. Pure gold ✓ Correct
D. Sea water
Solution: Pure gold is made of only gold, so it is a pure substance. Sea water, air and soup are all mixtures of different substances.
Q4 — Pure Substances · easy · theory
Table salt is called a pure substance because it ______.
A. can be split into water and sugar
B. has the same composition throughout ✓ Correct
C. is a mixture of many salts
D. keeps changing its composition
Solution: Every part of pure table salt is the same, so it has a fixed composition throughout — that is what makes it a pure substance.
Q5 — Pure Substances · medium · theory
Which property is TRUE for a pure substance?
A. It has a fixed melting and boiling point ✓ Correct
B. It has no fixed melting point
C. It always contains water
D. It is always a liquid
Solution: A pure substance always melts and boils at fixed temperatures. A mixture usually does not have a single fixed melting or boiling point.
Q6 — Pure Substances · medium · theory
Distilled water boils at exactly 100°C at sea level, but sea water boils at a slightly higher temperature. This shows that ______.
A. both are pure substances
B. water is never a pure substance
C. sea water is purer than distilled water
D. distilled water is pure while sea water is a mixture ✓ Correct
Solution: A pure substance boils at one fixed temperature. The salt dissolved in sea water changes its boiling point, showing sea water is a mixture.
Q7 — Pure Substances · medium · theory
Which one of these is NOT a pure substance?
A. Orange juice ✓ Correct
B. Diamond
C. Oxygen gas
D. Copper
Solution: Orange juice is a mixture of water, sugars, acids and pulp. Diamond, copper and oxygen are each made of only one kind of particle.
Q8 — Pure Substances · medium · theory
Sugar taken from a sugar packet is a pure substance mainly because ______.
A. it is white in colour
B. every grain has the same composition ✓ Correct
C. it tastes sweet
D. it dissolves in water
Solution: Being sweet, white or able to dissolve are just properties. It is called pure because every grain has exactly the same composition.
Q9 — Pure Substances · hard · theory
Which set contains ONLY pure substances?
A. Gold, oxygen and distilled water ✓ Correct
B. Brass, water and diamond
C. Salt water, sugar and iron
D. Milk, gold and air
Solution: Gold, oxygen and distilled water are all pure. The other sets include mixtures — milk, air, salt water and brass (a mix of metals) are not pure.
Q10 — Pure Substances · hard · theory
Ravi has a shiny yellow metal. It melts at one fixed temperature and cannot be broken down into simpler substances by any physical method. The metal is most likely ______.
A. a mixture of metals
B. brass
C. muddy water
D. pure gold, a pure substance ✓ Correct
Solution: A fixed melting point and being impossible to separate physically are signs of a pure substance, so the metal is most likely pure gold.