21Our stomach produces which acid to help digestion?AAcetic acidBNitric acidCSulphuric acidDHydrochloric acidView AnswerDiscussWorkspaceReportSaveEasy
22Which is the hardest natural substance?AGraphiteBDiamondCQuartzDIronView AnswerDiscussWorkspaceReportSaveEasy
23Lemons are sour because they contain:ACitric acidBAcetic acidCFormic acidDTartaric acid onlyView AnswerDiscussWorkspaceReportSaveEasy
24The process of coating iron with zinc to prevent rusting is:AGalvanisationBVulcanisationCElectrolysisDCalcinationView AnswerDiscussWorkspaceReportSaveEasy