Basic Concepts of ChemistryPhysical and Chemical Changes16Choose the best answerWhich of the following is a reversible physical change?AGrinding wood into sawdustBCutting down a treeCHeating an iron nail and allowing it to coolDBoth A and B Like 0 Discuss 0Share
Basic Concepts of ChemistryMatter and its Classification17Choose the best answerWhich type of matter can have variable composition?AA pure substanceBAn elementCBoth homogeneous and heterogeneous mixturesDA compound Like 0 Discuss 0Share
Basic Concepts of ChemistryPhysical and Chemical Changes18Choose the best answerSolid → Liquid → Gas involves the sequence:AFreezing → BoilingBMelting → BoilingCSublimation → DepositionDMelting → Freezing Like 0 Discuss 0Share
Basic Concepts of ChemistryAtoms, Molecules and Ions19Choose the best answerWhat is the smallest unit of an element that retains the properties of that element?AMoleculeBAtomCIonDElectron Like 0 Discuss 0Share
Basic Concepts of ChemistryPhysical and Chemical Changes20Choose the best answerSolid → Gas directly, without becoming liquid, is called:AMeltingBBoilingCSublimationDDeposition Like 0 Discuss 0Share