{"id":84764,"date":"2025-06-01T02:49:29","date_gmt":"2025-06-01T02:49:29","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=84764"},"modified":"2025-06-01T02:49:29","modified_gmt":"2025-06-01T02:49:29","slug":"which-of-the-following-substances-cause-temporary-hardness-in-water","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/","title":{"rendered":"Which of the following substances cause temporary hardness in water?"},"content":{"rendered":"<p>Which of the following substances cause temporary hardness in water?<\/p>\n<ul>\n<li>1. Mg(HCO<sub>3<\/sub>)<sub>2<\/sub><\/li>\n<li>2. Ca(HCO<sub>3<\/sub>)<sub>2<\/sub><\/li>\n<li>3. CaCl<sub>2<\/sub><\/li>\n<li>4. MgSO<sub>4<\/sub><\/li>\n<\/ul>\n<p>Select the correct answer using the code given below.<\/p>\n<p>[amp_mcq option1=&#8221;3 and 4&#8243; option2=&#8221;2 and 3&#8243; option3=&#8221;1 and 4&#8243; option4=&#8221;1 and 2&#8243; correct=&#8221;option4&#8243;]<\/p>\n<div class=\"psc-box-pyq-exam-year-detail\">\n<div class=\"pyq-exam\">\n<div class=\"psc-heading\">This question was previously asked in<\/div>\n<div class=\"psc-title line-ellipsis\">UPSC CDS-1 &#8211; 2018<\/div>\n<\/div>\n<div class=\"pyq-exam-psc-buttons\"><a href=\"\/pyq\/pyq-upsc-cds-1-2018.pdf\" target=\"_blank\" class=\"psc-pdf-button\" rel=\"noopener\">Download PDF<\/a><a href=\"\/pyq-upsc-cds-1-2018\" target=\"_blank\" class=\"psc-attempt-button\" rel=\"noopener\">Attempt Online<\/a><\/div>\n<\/div>\n<section id=\"pyq-correct-answer\">\nTemporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness.<br \/>\nFrom the given list:<br \/>\n1. Mg(HCO3)2 &#8211; Magnesium bicarbonate (causes temporary hardness)<br \/>\n2. Ca(HCO3)2 &#8211; Calcium bicarbonate (causes temporary hardness)<br \/>\n3. CaCl2 &#8211; Calcium chloride (causes permanent hardness)<br \/>\n4. MgSO4 &#8211; Magnesium sulfate (causes permanent hardness)<br \/>\nTherefore, substances 1 and 2 cause temporary hardness.<br \/>\n<\/section>\n<section id=\"pyq-key-points\">\nTemporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.<br \/>\n<\/section>\n<section id=\"pyq-additional-information\">\nPermanent hardness is caused by dissolved sulfates and chlorides of calcium and magnesium. It cannot be removed by simple boiling but requires other methods like ion exchange or chemical precipitation using agents like washing soda.<br \/>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Which of the following substances cause temporary hardness in water? 1. Mg(HCO3)2 2. Ca(HCO3)2 3. CaCl2 4. MgSO4 Select the correct answer using the code given below. [amp_mcq option1=&#8221;3 and 4&#8243; option2=&#8221;2 and 3&#8243; option3=&#8221;1 and 4&#8243; option4=&#8221;1 and 2&#8243; correct=&#8221;option4&#8243;] This question was previously asked in UPSC CDS-1 &#8211; 2018 Download PDFAttempt Online Temporary &#8230; <\/p>\n<p class=\"read-more-container\"><a title=\"Which of the following substances cause temporary hardness in water?\" class=\"read-more button\" href=\"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/#more-84764\">Detailed Solution<span class=\"screen-reader-text\">Which of the following substances cause temporary hardness in water?<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1087],"tags":[1114,1096,1161],"class_list":["post-84764","post","type-post","status-publish","format-standard","hentry","category-upsc-cds-1","tag-1114","tag-chemistry","tag-hydrogen-and-its-compounds","no-featured-image-padding"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v22.2 (Yoast SEO v23.3) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Which of the following substances cause temporary hardness in water?<\/title>\n<meta name=\"description\" content=\"Temporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness. From the given list: 1. Mg(HCO3)2 - Magnesium bicarbonate (causes temporary hardness) 2. Ca(HCO3)2 - Calcium bicarbonate (causes temporary hardness) 3. CaCl2 - Calcium chloride (causes permanent hardness) 4. MgSO4 - Magnesium sulfate (causes permanent hardness) Therefore, substances 1 and 2 cause temporary hardness. Temporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Which of the following substances cause temporary hardness in water?\" \/>\n<meta property=\"og:description\" content=\"Temporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness. From the given list: 1. Mg(HCO3)2 - Magnesium bicarbonate (causes temporary hardness) 2. Ca(HCO3)2 - Calcium bicarbonate (causes temporary hardness) 3. CaCl2 - Calcium chloride (causes permanent hardness) 4. MgSO4 - Magnesium sulfate (causes permanent hardness) Therefore, substances 1 and 2 cause temporary hardness. Temporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T02:49:29+00:00\" \/>\n<meta name=\"author\" content=\"rawan239\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"rawan239\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"Which of the following substances cause temporary hardness in water?","description":"Temporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness. From the given list: 1. Mg(HCO3)2 - Magnesium bicarbonate (causes temporary hardness) 2. Ca(HCO3)2 - Calcium bicarbonate (causes temporary hardness) 3. CaCl2 - Calcium chloride (causes permanent hardness) 4. MgSO4 - Magnesium sulfate (causes permanent hardness) Therefore, substances 1 and 2 cause temporary hardness. Temporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/","og_locale":"en_US","og_type":"article","og_title":"Which of the following substances cause temporary hardness in water?","og_description":"Temporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness. From the given list: 1. Mg(HCO3)2 - Magnesium bicarbonate (causes temporary hardness) 2. Ca(HCO3)2 - Calcium bicarbonate (causes temporary hardness) 3. CaCl2 - Calcium chloride (causes permanent hardness) 4. MgSO4 - Magnesium sulfate (causes permanent hardness) Therefore, substances 1 and 2 cause temporary hardness. Temporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T02:49:29+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/","url":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/","name":"Which of the following substances cause temporary hardness in water?","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T02:49:29+00:00","dateModified":"2025-06-01T02:49:29+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"Temporary hardness in water is caused by the presence of dissolved bicarbonates of calcium (Ca(HCO3)2) and magnesium (Mg(HCO3)2). These compounds decompose when water is boiled, forming insoluble calcium carbonate and magnesium carbonate, which precipitate out, thereby removing the hardness. From the given list: 1. Mg(HCO3)2 - Magnesium bicarbonate (causes temporary hardness) 2. Ca(HCO3)2 - Calcium bicarbonate (causes temporary hardness) 3. CaCl2 - Calcium chloride (causes permanent hardness) 4. MgSO4 - Magnesium sulfate (causes permanent hardness) Therefore, substances 1 and 2 cause temporary hardness. Temporary hardness is primarily caused by dissolved calcium and magnesium bicarbonates.","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/which-of-the-following-substances-cause-temporary-hardness-in-water\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/exam.pscnotes.com\/mcq\/"},{"@type":"ListItem","position":2,"name":"UPSC CDS-1","item":"https:\/\/exam.pscnotes.com\/mcq\/category\/upsc-cds-1\/"},{"@type":"ListItem","position":3,"name":"Which of the following substances cause temporary hardness in water?"}]},{"@type":"WebSite","@id":"https:\/\/exam.pscnotes.com\/mcq\/#website","url":"https:\/\/exam.pscnotes.com\/mcq\/","name":"MCQ and Quiz for Exams","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/exam.pscnotes.com\/mcq\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209","name":"rawan239","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","caption":"rawan239"},"sameAs":["https:\/\/exam.pscnotes.com"],"url":"https:\/\/exam.pscnotes.com\/mcq\/author\/rawan239\/"}]}},"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/84764","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/comments?post=84764"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/84764\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=84764"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=84764"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=84764"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}