MCQ
Hardness of water MCQ - Practice Questions with Answers
Solve 1 Hardness of water questions for RAS/RPSC preparation.
Practice questions
Q1Which salt is used to remove the permanent hardness of water?
Explanation
Permanent hardness is mainly caused by calcium and magnesium sulphates or chlorides. Washing soda, sodium carbonate decahydrate, Na2CO3.10H2O, removes this hardness by precipitating calcium and magnesium ions as insoluble carbonates. Bleaching powder, CaOCl2, is used chiefly for disinfection and bleaching, not for removing permanent hardness. Sodium bicarbonate, NaHCO3, is not the standard salt used for this purpose. Gypsum, CaSO4.2H2O, is itself a calcium salt and can contribute to hardness rather than remove it.
You've seen 1 of 1 sample questions
Unlimited practice on Hardness of water comes with the RAS Test Series + Practice pack or Gate Pass.
More topics in Science & Technology
Defence & Space TechnologyRecent Advancements & Indian ContributionsComputers & ICTHealth, Food & NutritionGenetics, Biotechnology & NanotechnologyEveryday ScienceGovernment S&T Programs & PoliciesBasics of Everyday ScienceNuclear EnergyAgriculture, Horticulture & Animal HusbandryDefence TechnologyGeneral ScienceEarth Observation SatellitePlant EvolutionAtomic Energy RegulationSmart MaterialsElectrochromic DevicesSatellite SystemsNuclear Reactor DesignRegulatory GovernanceThree-Stage Nuclear ProgrammeBirbal Sahni Institute Jamun StudyNuclear SafetyPublic HealthHydrocarbons & EnergyFast Breeder ReactorsDigital Health MissionResearch and InnovationConnected VehiclesStartupsHigh-Speed RailAI in GovernanceCivil AviationElectronics ManufacturingSpace Sector ReformsIndigenisationSmall Modular ReactorsSemiconductorsIndustry-Academia CollaborationPrivate Space SectorKavachGreen Steel and DecarbonisationAviation InfrastructureSemiconductor MissionSpace TechnologyDefence IndigenisationSpace ProgrammeIndian RailwaysSpace MissionsNuclear ProgrammeISRO Lunar MissionsMeteorologyGreen Mobility and Hydrogen MissionISROScientific InstitutionsSpace ExplorationNational Technology DayIndia Modern HistoryIndian Railways Hydrogen TrainIndian Railways and Green MobilitySpace AwardsIndigenous Hydrogen Fuel Cell TrainMission MausamIndia Semiconductor MissionNaval ModernisationPublic ConsultationAERB RegulationScience & TechnologySatellite MeteorologyGeneral KnowledgeVande Bharat ManufacturingVande BharatAgriculture, horticulture, forestry & animal husbandry; Rajasthan focus and economic importanceupsc-p1-science-tech-biotechnologyHuman body, blood groups, genetics and common diseasesHuman body, blood groups and common diseasesupsc-p1-science-tech-blockchain-quantumupsc-p1-science-tech-cell-geneticsDefence, space and nuclear technology of IndiaSpace, biotechnology and recent science developmentsupsc-p1-science-tech-physics-applicationsupsc-p1-science-tech-nuclearupsc-p1-science-tech-health-diseasesupsc-p1-science-tech-human-physiologyupsc-p1-science-tech-it-computers-aiupsc-p1-science-tech-defenceupsc-p1-science-tech-iprupsc-p1-science-tech-measurement-unitsupsc-p1-science-tech-robotics-emergingupsc-p1-science-tech-spaceupsc-p1-science-tech-chemistry-applicationsupsc-p1-science-tech-nanotechnologyDefenceupsc-p1-science-tech-communication-5gupsc-p1-science-tech-in-newsupsc-p1-geography-universe-solar-systemupsc-p1-current-affairs-science-tech-newsCritical Mineralsupsc-p1-environment-renewable-energyPhysical and chemical changesTechnology Readiness LevelHuman geneticsBlood groupsDrug RegulationChemical reactions of metalsHuman eye and optical defectsAllotropes of carbonDRDO Cruise MissileOilseeds Kisan MitraResearch PolicySHANTI Act 2025India-Korea Space DaySemiconductor EcosystemNational Health Research PolicyNISAR earthquake mappingNISAR Urgent ResponseDrone-assisted TB diagnosisAI RegulationTelecommunicationsBattery RecyclingDigital IndiaGenetics and heredityTraditional MedicineUIDAI BiometricsICMRKavach ATP SystemInternational Chemistry OlympiadInternational Physics Olympiadupsc-p1-environment-agriculture-environmentINCOIS and El Niño BulletinPharma/Drugs RulesRajasthan GKLight reflection in plane mirrorsBlood groups and transfusion compatibilityMedicinal plant partsOptics: dispersion through prismOptics: reflection of lightOrganic chemistry: hydrogenation of oilsOrganic chemistry: vital force theoryOxidation and reductionOxidation of alcoholsPalaeobotanyParallel resistancePlane mirrors and image formationPolymerase chain reactionPolymersPrivacy and ConsentProject 17A stealth frigateQdenga clinical evidenceQuantum & Semiconductor MissionsRedox reactionsRenewable energy technologiesSatellite orbitsSatellite television and communicationScience and Technology Resource CentreScience and technology programmes in RajasthanSinchan 2026SupercomputingTelephone communication deviceThermodynamics: internal energyTime Synchronisation NetworkTranslational health researchVikram-1 MissionVitamins and deficiency diseasesVitamins and nutritionupsc-p1-current-affairs-defence-securityupsc-p1-economy-infrastructure-pppMirrors and field of viewAadhaarAcid-base neutralisationAcidic and basic nature of oxidesAcids and carbonatesAcids in plants and stingsAcids, bases and saltsAgriculture: seed certificationAlloysAnimal diseasesAntiseptics and disinfectantsApicultureAqua regiaArtificial satellitesAtal Innovation MissionAwards and AchievementsBacterial shapesBiometrics and AadhaarBiomolecules and natural fibresBiotechnology: animal cloningBiotechnology: single cell proteinBlood transfusion and blood groupsCBRN PreparednessCSIR full formCapacitance and dielectricsCarbon and its compoundsCell biology: chromosome structureChemical equilibrium and catalysisChemical kinetics and autocatalysisChemical properties of sodiumChemical reactions and catalysisChemical reactions and heat changeChemical reactions and precipitatesCloud seedingCoal types and carbon contentColour blindnessCommon chemical compoundsCommunicable diseasesConcave mirror image formationConservation of mechanical energyCorrosion of copperCritical Minerals and Battery RecyclingCrystal lattice and densityDNA nitrogenous basesDefects of visionDengue vaccine technologyDensity and flotationDepartment of Atomic Energy and HBCSEDigestive enzymesDigital EconomyDisplacement reactionsDwarf planetsEarth's magnetismEconomic insectsEconomically important plantsElectric circuits: series resistanceElectric fuse and circuit safetyElectrical resistivityElectrolysis and Faraday's lawElectronic configuration and metallic characterEnergy conversion in enginesEquivalent weight of KMnO4Escape velocityEthylene glycol and antifreezeEveryday chemistryFatty acids and oilsFishery and aquacultureFlex Fuel VehiclesGPS and navigation systemsGenetic codeGenetic disordersGenetic engineeringGenetics: monohybrid crossGeostationary satellitesGreen HydrogenHealthHistory of molecular biologyHuman chromosomesHuman dentitionHuman diseases and parasitesHuman diseases and pathogensHuman endocrine systemHuman insulin structureHuman physiology: opioid receptorsISRO launch vehiclesImmunology antibodiesImmunosuppressants and organ transplantationIndia-EU CooperationIndia-EU TTCIndia-EU Trade and Technology CouncilIndian Standard Time DistributionIndian space research centresIndian-origin space travellersIndigenous hyperloop systemIndigenous warship designInternational Physics Olympiad 2026International Science Olympiads 2026Launch Vehicle TechnologyLens formulaLi-Fi technologyLight: refraction and scatteringMagnetic dipole moment of a coilMaterials Science and Energy StorageMendelian geneticsMendelian inheritanceMetallurgy processesMetallurgy: anodisingMicrobial industrial productsMicrobial products in medicineMissile SpecificationsNatural dyes and pigmentsNuclear Energy and SafetyNuclear Hydrogen ProductionNutrition and microorganismsOceanographyOptics: dispersion and recombination of white light