21Which colour of light has the longest wavelength?ABlueBRedCVioletDGreenView AnswerDiscussWorkspaceReportSaveEasy
22Work done is zero when the force and displacement are:APerpendicularBIn the same directionCOppositeDBoth zero onlyView AnswerDiscussWorkspaceReportSaveEasy
23A body's mass is 60 kg on Earth. What is its mass on the Moon?A0 kgB10 kgC60 kgD360 kgView AnswerDiscussWorkspaceReportSaveMedium
24Echo is caused by the:ARefraction of soundBReflection of soundCDiffraction of soundDAbsorption of soundView AnswerDiscussWorkspaceReportSaveEasy