Is Matter Around Us PurePractice Questions & MCQs

Q1. Why is crystallisation often preferred over evaporation to purify a solid?

• A.some solids decompose on strong heating, which crystallisation avoids
• B.evaporation is impossible for solids
• C.crystallisation needs no solvent
• D.evaporation always adds impurities

Answer: A. some solids decompose on strong heating, which crystallisation avoids

Q2. Why must a mixture of salt and water NOT be separated by filtration?

• A.the salt is dissolved and passes through the filter paper
• B.salt is magnetic and sticks to the funnel
• C.water cannot pass through filter paper
• D.the salt reacts with the paper

Answer: A. the salt is dissolved and passes through the filter paper

Q3. Which separation relies on a difference in particle SIZE (insoluble solids vs liquid)?

• A.filtration
• B.distillation
• C.chromatography
• D.a separating funnel

Answer: A. filtration

The core fact here is - An ion forms when an atom gains or loses electrons; charge = (protons) - (electrons), so the sign and magnitude follow directly => substituting the given counts gives the stated species; therefore the answer = filtration. That fits the listed correct option directly - Correct. As for the rest: option B) 'distillation' is incorrect: Distillation relies on boiling-point differences, not particle size; option C) 'chromatography' misses the point - Chromatography relies on differing movement rates, not simple size sieving. Hence the answer is A) filtration.