16Which gas is used in filling electric bulbs?AArgonBCarbon dioxideCOxygenDHydrogenView AnswerDiscussWorkspaceReportSaveEasy
17The most abundant metal in Earth's crust is:ACalciumBCopperCIronDAluminiumView AnswerDiscussWorkspaceReportSaveEasy
18The chemical formula of common salt is:ANaClBKClCNa₂CO₃DNaOHView AnswerDiscussWorkspaceReportSaveEasy
19Our stomach produces which acid to help digestion?AAcetic acidBHydrochloric acidCSulphuric acidDNitric acidView AnswerDiscussWorkspaceReportSaveEasy